21204431040 has 112 divisors (see below), whose sum is σ = 72502885728. Its totient is φ = 5219549184.

The previous prime is 21204431023. The next prime is 21204431051. The reversal of 21204431040 is 4013440212.

It is a junction number, because it is equal to n+sod(n) for n = 21204430998 and 21204431016.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 837057 + ... + 862016.

It is an arithmetic number, because the mean of its divisors is an integer number (647347194).

Almost surely, 2^21204431040 is an apocalyptic number.

21204431040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21204431040 is an abundant number, since it is smaller than the sum of its proper divisors (51298454688).

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

21204431040 is a wasteful number, since it uses less digits than its factorization.

21204431040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1699106 (or 1699096 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 21.

Adding to 21204431040 its reverse (4013440212), we get a palindrome (25217871252).

The spelling of 21204431040 in words is "twenty-one billion, two hundred four million, four hundred thirty-one thousand, forty".