21292157 has 4 divisors (see below), whose sum is σ = 21371580. Its totient is φ = 21212736.

The previous prime is 21292153. The next prime is 21292163. The reversal of 21292157 is 75129212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8231161 + 13060996 = 2869^2 + 3614^2 .

It is a cyclic number.

It is not a de Polignac number, because 21292157 - 2² = 21292153 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 (21292153) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39308 + ... + 39845.

It is an arithmetic number, because the mean of its divisors is an integer number (5342895).

Almost surely, 2^21292157 is an apocalyptic number.

It is an amenable number.

21292157 is a deficient number, since it is larger than the sum of its proper divisors (79423).

21292157 is an equidigital number, since it uses as much as digits as its factorization.

21292157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79422.

The product of its digits is 2520, while the sum is 29.

The square root of 21292157 is about 4614.3425317157. The cubic root of 21292157 is about 277.1659568451.

The spelling of 21292157 in words is "twenty-one million, two hundred ninety-two thousand, one hundred fifty-seven".