21583871720 has 32 divisors (see below), whose sum is σ = 48567983400. Its totient is φ = 8632789248.

The previous prime is 21583871707. The next prime is 21583871723. The reversal of 21583871720 is 2717838512.

It can be written as a sum of positive squares in 4 ways, for example, as 20615790724 + 968080996 = 143582^2 + 31114^2 .

It is not an unprimeable number, because it can be changed into a prime (21583871723) 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, 740462 + ... + 769058.

Almost surely, 2^21583871720 is an apocalyptic number.

21583871720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21583871720 is an abundant number, since it is smaller than the sum of its proper divisors (26984111680).

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

21583871720 is a wasteful number, since it uses less digits than its factorization.

21583871720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47477 (or 47473 counting only the distinct ones).

The product of its (nonzero) digits is 188160, while the sum is 44.

The spelling of 21583871720 in words is "twenty-one billion, five hundred eighty-three million, eight hundred seventy-one thousand, seven hundred twenty".