21487408820 has 24 divisors (see below), whose sum is σ = 46579158528. Its totient is φ = 8317706400.

The previous prime is 21487408793. The next prime is 21487408847. The reversal of 21487408820 is 2880478412.

It is an interprime number because it is at equal distance from previous prime (21487408793) and next prime (21487408847).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17327936 + ... + 17329175.

It is an arithmetic number, because the mean of its divisors is an integer number (1940798272).

Almost surely, 2^21487408820 is an apocalyptic number.

21487408820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21487408820 is an abundant number, since it is smaller than the sum of its proper divisors (25091749708).

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

21487408820 is a wasteful number, since it uses less digits than its factorization.

21487408820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34657151 (or 34657149 counting only the distinct ones).

The product of its (nonzero) digits is 229376, while the sum is 44.

The spelling of 21487408820 in words is "twenty-one billion, four hundred eighty-seven million, four hundred eight thousand, eight hundred twenty".