21901257 has 48 divisors (see below), whose sum is σ = 37914240. Its totient is φ = 11923200.

The previous prime is 21901247. The next prime is 21901259. The reversal of 21901257 is 75210912.

It is not a de Polignac number, because 21901257 - 2⁶ = 21901193 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21901257.

It is not an unprimeable number, because it can be changed into a prime (21901259) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 157494 + ... + 157632.

It is an arithmetic number, because the mean of its divisors is an integer number (789880).

Almost surely, 2^21901257 is an apocalyptic number.

It is an amenable number.

21901257 is a deficient number, since it is larger than the sum of its proper divisors (16012983).

21901257 is a wasteful number, since it uses less digits than its factorization.

21901257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 254 (or 251 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 21901257 is about 4679.8778830222. The cubic root of 21901257 is about 279.7840895047.

The spelling of 21901257 in words is "twenty-one million, nine hundred one thousand, two hundred fifty-seven".