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21381376 = 28174
BaseRepresentation
bin101000110010…
…0000100000000
31111020021201211
41101210010000
520433201001
62042135504
7346511242
oct121440400
944207654
1021381376
1111084165
1271b1594
134578103
142ba8092
151d25351
hex1464100

21381376 has 45 divisors (see below), whose sum is σ = 45346651. Its totient is φ = 10061824.

The previous prime is 21381361. The next prime is 21381379. The reversal of 21381376 is 67318312.

The square root of 21381376 is 4624.

It is a perfect power (a square, a biquadrate), and thus also a powerful number.

It can be written as a sum of positive squares in 2 ways, for example, as 6635776 + 14745600 = 2576^2 + 3840^2 .

It is a Duffinian number.

Its product of digits (6048) is a multiple of the sum of its prime factors (84).

It is not an unprimeable number, because it can be changed into a prime (21381379) by changing a digit.

It is a polite number, since it can be written in 4 ways as a sum of consecutive naturals, for example, 1257720 + ... + 1257736.

Almost surely, 221381376 is an apocalyptic number.

21381376 is the 4624-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21381376

21381376 is an abundant number, since it is smaller than the sum of its proper divisors (23965275).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21381376 is an frugal number, since it uses more digits than its factorization.

21381376 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84 (or 19 counting only the distinct ones).

The product of its digits is 6048, while the sum is 31.

The cubic root of 21381376 is about 277.5525469304.

Adding to 21381376 its reverse (67318312), we get a palindrome (88699688).

The spelling of 21381376 in words is "twenty-one million, three hundred eighty-one thousand, three hundred seventy-six".

Divisors: 1 2 4 8 16 17 32 34 64 68 128 136 256 272 289 544 578 1088 1156 2176 2312 4352 4624 4913 9248 9826 18496 19652 36992 39304 73984 78608 83521 157216 167042 314432 334084 628864 668168 1257728 1336336 2672672 5345344 10690688 21381376