20131131 has 4 divisors (see below), whose sum is σ = 26841512. Its totient is φ = 13420752.

The previous prime is 20131129. The next prime is 20131147. The reversal of 20131131 is 13113102.

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

It is not a de Polignac number, because 20131131 - 2¹ = 20131129 is a prime.

It is a super-2 number, since 2×20131131² = 810524870678322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20131031) 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, 3355186 + ... + 3355191.

It is an arithmetic number, because the mean of its divisors is an integer number (6710378).

Almost surely, 2^20131131 is an apocalyptic number.

20131131 is a deficient number, since it is larger than the sum of its proper divisors (6710381).

20131131 is an equidigital number, since it uses as much as digits as its factorization.

20131131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6710380.

The product of its (nonzero) digits is 18, while the sum is 12.

The square root of 20131131 is about 4486.7728937400. The cubic root of 20131131 is about 272.0337103188.

Adding to 20131131 its reverse (13113102), we get a palindrome (33244233).

The spelling of 20131131 in words is "twenty million, one hundred thirty-one thousand, one hundred thirty-one".