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21640080 = 24357111171
BaseRepresentation
bin101001010001…
…1001110010000
31111201102121110
41102203032100
521014440310
62051453320
7351636420
oct122431620
944642543
1021640080
1111240570
1272b7240
134638aa7
142c34480
151d76d20
hex14a3390

21640080 has 160 divisors (see below), whose sum is σ = 83708928. Its totient is φ = 4492800.

The previous prime is 21640067. The next prime is 21640081. The reversal of 21640080 is 8004612.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21640081) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17895 + ... + 19065.

Almost surely, 221640080 is an apocalyptic number.

21640080 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21640080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41854464).

21640080 is an abundant number, since it is smaller than the sum of its proper divisors (62068848).

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

21640080 is a wasteful number, since it uses less digits than its factorization.

21640080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1205 (or 1199 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21640080 is about 4651.8899385089. The cubic root of 21640080 is about 278.6674781028.

Adding to 21640080 its reverse (8004612), we get a palindrome (29644692).

The spelling of 21640080 in words is "twenty-one million, six hundred forty thousand, eighty".