21566015416 has 128 divisors (see below), whose sum is σ = 47421158400. Its totient is φ = 9100672000.

The previous prime is 21566015357. The next prime is 21566015447. The reversal of 21566015416 is 61451066512.

It is a congruent number.

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, 7427421 + ... + 7430323.

It is an arithmetic number, because the mean of its divisors is an integer number (370477800).

Almost surely, 2^21566015416 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 21566015416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23710579200).

21566015416 is an abundant number, since it is smaller than the sum of its proper divisors (25855142984).

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

21566015416 is a wasteful number, since it uses less digits than its factorization.

21566015416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3061 (or 3057 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 37.

The spelling of 21566015416 in words is "twenty-one billion, five hundred sixty-six million, fifteen thousand, four hundred sixteen".