21365656554 has 64 divisors (see below), whose sum is σ = 47468384640. Its totient is φ = 6410096000.

The previous prime is 21365656517. The next prime is 21365656583. The reversal of 21365656554 is 45565656312.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 793342 + ... + 819830.

It is an arithmetic number, because the mean of its divisors is an integer number (741693510).

Almost surely, 2^21365656554 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21365656554, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23734192320).

21365656554 is an abundant number, since it is smaller than the sum of its proper divisors (26102728086).

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

21365656554 is a wasteful number, since it uses less digits than its factorization.

21365656554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26628 (or 26606 counting only the distinct ones).

The product of its digits is 3240000, while the sum is 48.

The spelling of 21365656554 in words is "twenty-one billion, three hundred sixty-five million, six hundred fifty-six thousand, five hundred fifty-four".