21131112020 has 24 divisors (see below), whose sum is σ = 44517122664. Its totient is φ = 8425437696.

The previous prime is 21131111959. The next prime is 21131112109. The reversal of 21131112020 is 2021113112.

It can be written as a sum of positive squares in 4 ways, for example, as 1084516624 + 20046595396 = 32932^2 + 141586^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21131111986 and 21131112004.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1681529 + ... + 1694048.

It is an arithmetic number, because the mean of its divisors is an integer number (1854880111).

Almost surely, 2^21131112020 is an apocalyptic number.

21131112020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21131112020 is an abundant number, since it is smaller than the sum of its proper divisors (23386010644).

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

21131112020 is a wasteful number, since it uses less digits than its factorization.

21131112020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3375899 (or 3375897 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21131112020 its reverse (2021113112), we get a palindrome (23152225132).

The spelling of 21131112020 in words is "twenty-one billion, one hundred thirty-one million, one hundred twelve thousand, twenty".