21383172 has 18 divisors (see below), whose sum is σ = 54051998. Its totient is φ = 7127712.

The previous prime is 21383143. The next prime is 21383177. The reversal of 21383172 is 27138312.

It can be written as a sum of positive squares in only one way, i.e., 17438976 + 3944196 = 4176^2 + 1986^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is not an unprimeable number, because it can be changed into a prime (21383177) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 296953 + ... + 297024.

Almost surely, 2^21383172 is an apocalyptic number.

It is an amenable number.

21383172 is an abundant number, since it is smaller than the sum of its proper divisors (32668826).

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

21383172 is a wasteful number, since it uses less digits than its factorization.

21383172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 593987 (or 593982 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 21383172 is about 4624.1942000742. The cubic root of 21383172 is about 277.5603180301.

The spelling of 21383172 in words is "twenty-one million, three hundred eighty-three thousand, one hundred seventy-two".