21257892 has 36 divisors (see below), whose sum is σ = 54478060. Its totient is φ = 6988032.

The previous prime is 21257881. The next prime is 21257893. The reversal of 21257892 is 29875212.

It can be written as a sum of positive squares in 2 ways, for example, as 4562496 + 16695396 = 2136^2 + 4086^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21257893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1417 + ... + 6672.

Almost surely, 2^21257892 is an apocalyptic number.

It is an amenable number.

21257892 is an abundant number, since it is smaller than the sum of its proper divisors (33220168).

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

21257892 is a wasteful number, since it uses less digits than its factorization.

21257892 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8172 (or 8167 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21257892 is about 4610.6281567700. The cubic root of 21257892 is about 277.0171979921.

The spelling of 21257892 in words is "twenty-one million, two hundred fifty-seven thousand, eight hundred ninety-two".