21684131024 has 20 divisors (see below), whose sum is σ = 43461729060. Its totient is φ = 10468200960.

The previous prime is 21684130987. The next prime is 21684131033. The reversal of 21684131024 is 42013148612.

It can be written as a sum of positive squares in 2 ways, for example, as 12823297600 + 8860833424 = 113240^2 + 94132^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23366057 + ... + 23366984.

It is an arithmetic number, because the mean of its divisors is an integer number (2173086453).

Almost surely, 2^21684131024 is an apocalyptic number.

It is an amenable number.

21684131024 is an abundant number, since it is smaller than the sum of its proper divisors (21777598036).

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

21684131024 is a wasteful number, since it uses less digits than its factorization.

21684131024 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46733078 (or 46733072 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 32.

Adding to 21684131024 its reverse (42013148612), we get a palindrome (63697279636).

The spelling of 21684131024 in words is "twenty-one billion, six hundred eighty-four million, one hundred thirty-one thousand, twenty-four".