21901157 has 4 divisors (see below), whose sum is σ = 22209696. Its totient is φ = 21592620.

The previous prime is 21901153. The next prime is 21901163. The reversal of 21901157 is 75110912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21901157 - 2² = 21901153 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21901153) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 154163 + ... + 154304.

It is an arithmetic number, because the mean of its divisors is an integer number (5552424).

Almost surely, 2^21901157 is an apocalyptic number.

It is an amenable number.

21901157 is a deficient number, since it is larger than the sum of its proper divisors (308539).

21901157 is an equidigital number, since it uses as much as digits as its factorization.

21901157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 308538.

The product of its (nonzero) digits is 630, while the sum is 26.

The square root of 21901157 is about 4679.8671989705. The cubic root of 21901157 is about 279.7836636775.

The spelling of 21901157 in words is "twenty-one million, nine hundred one thousand, one hundred fifty-seven".