21987334656 has 800 divisors, whose sum is σ = 81280869120. Its totient is φ = 5780865024.

The previous prime is 21987334639. The next prime is 21987334661. The reversal of 21987334656 is 65643378912.

21987334656 is a `hidden beast` number, since 21 + 98 + 73 + 3 + 465 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 247048660 + ... + 247048748.

Almost surely, 2^21987334656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21987334656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40640434560).

21987334656 is an abundant number, since it is smaller than the sum of its proper divisors (59293534464).

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

21987334656 is an equidigital number, since it uses as much as digits as its factorization.

21987334656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186 (or 161 counting only the distinct ones).

The product of its digits is 6531840, while the sum is 54.

The spelling of 21987334656 in words is "twenty-one billion, nine hundred eighty-seven million, three hundred thirty-four thousand, six hundred fifty-six".