21311131020 has 24 divisors (see below), whose sum is σ = 59671167024. Its totient is φ = 5682968256.

The previous prime is 21311131019. The next prime is 21311131027. The reversal of 21311131020 is 2013111312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is not an unprimeable number, because it can be changed into a prime (21311131027) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 177592699 + ... + 177592818.

It is an arithmetic number, because the mean of its divisors is an integer number (2486298626).

Almost surely, 2^21311131020 is an apocalyptic number.

21311131020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21311131020 is an abundant number, since it is smaller than the sum of its proper divisors (38360036004).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21311131020 is a wasteful number, since it uses less digits than its factorization.

21311131020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355185529 (or 355185527 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 15.

Adding to 21311131020 its reverse (2013111312), we get a palindrome (23324242332).

The spelling of 21311131020 in words is "twenty-one billion, three hundred eleven million, one hundred thirty-one thousand, twenty".