20904157531 has 4 divisors (see below), whose sum is σ = 21168767200. Its totient is φ = 20639547864.

The previous prime is 20904157513. The next prime is 20904157577. The reversal of 20904157531 is 13575140902.

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 20904157531 - 2⁹ = 20904157019 is a prime.

It is a super-2 number, since 2×20904157531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20904157501) 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, 132304716 + ... + 132304873.

It is an arithmetic number, because the mean of its divisors is an integer number (5292191800).

Almost surely, 2^20904157531 is an apocalyptic number.

20904157531 is a deficient number, since it is larger than the sum of its proper divisors (264609669).

20904157531 is an equidigital number, since it uses as much as digits as its factorization.

20904157531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264609668.

The product of its (nonzero) digits is 37800, while the sum is 37.

The spelling of 20904157531 in words is "twenty billion, nine hundred four million, one hundred fifty-seven thousand, five hundred thirty-one".