21331881540 has 72 divisors (see below), whose sum is σ = 66083472000. Its totient is φ = 5567467584.

The previous prime is 21331881539. The next prime is 21331881551. The reversal of 21331881540 is 4518813312.

21331881540 is a `hidden beast` number, since 2 + 1 + 3 + 31 + 8 + 81 + 540 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21331881495 and 21331881504.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1252290 + ... + 1269209.

It is an arithmetic number, because the mean of its divisors is an integer number (917826000).

Almost surely, 2^21331881540 is an apocalyptic number.

21331881540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21331881540 is an abundant number, since it is smaller than the sum of its proper divisors (44751590460).

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

21331881540 is a wasteful number, since it uses less digits than its factorization.

21331881540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2521561 (or 2521556 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The spelling of 21331881540 in words is "twenty-one billion, three hundred thirty-one million, eight hundred eighty-one thousand, five hundred forty".