20157531 has 4 divisors (see below), whose sum is σ = 26876712. Its totient is φ = 13438352.

The previous prime is 20157517. The next prime is 20157551. The reversal of 20157531 is 13575102.

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 20157531 - 2¹⁵ = 20124763 is a prime.

It is a super-2 number, since 2×20157531² = 812652112031922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20157551) 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, 3359586 + ... + 3359591.

It is an arithmetic number, because the mean of its divisors is an integer number (6719178).

Almost surely, 2^20157531 is an apocalyptic number.

20157531 is a deficient number, since it is larger than the sum of its proper divisors (6719181).

20157531 is an equidigital number, since it uses as much as digits as its factorization.

20157531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6719180.

The product of its (nonzero) digits is 1050, while the sum is 24.

The square root of 20157531 is about 4489.7139107075. The cubic root of 20157531 is about 272.1525735341.

The spelling of 20157531 in words is "twenty million, one hundred fifty-seven thousand, five hundred thirty-one".