21157607 has 4 divisors (see below), whose sum is σ = 21309960. Its totient is φ = 21005256.

The previous prime is 21157601. The next prime is 21157627. The reversal of 21157607 is 70675112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21157607 - 2⁸ = 21157351 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21157607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21157601) 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, 75968 + ... + 76245.

It is an arithmetic number, because the mean of its divisors is an integer number (5327490).

Almost surely, 2^21157607 is an apocalyptic number.

21157607 is a deficient number, since it is larger than the sum of its proper divisors (152353).

21157607 is a wasteful number, since it uses less digits than its factorization.

21157607 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152352.

The product of its (nonzero) digits is 2940, while the sum is 29.

The square root of 21157607 is about 4599.7398839500. The cubic root of 21157607 is about 276.5808977536.

The spelling of 21157607 in words is "twenty-one million, one hundred fifty-seven thousand, six hundred seven".