21615666700 has 72 divisors (see below), whose sum is σ = 47366746112. Its totient is φ = 8561609280.

The previous prime is 21615666671. The next prime is 21615666727. The reversal of 21615666700 is 766651612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8164777 + ... + 8167423.

Almost surely, 2^21615666700 is an apocalyptic number.

21615666700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21615666700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23683373056).

21615666700 is an abundant number, since it is smaller than the sum of its proper divisors (25751079412).

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

21615666700 is a wasteful number, since it uses less digits than its factorization.

21615666700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3431 (or 3424 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 40.

The spelling of 21615666700 in words is "twenty-one billion, six hundred fifteen million, six hundred sixty-six thousand, seven hundred".