21655610416 has 80 divisors (see below), whose sum is σ = 47132081568. Its totient is φ = 9552384000.

The previous prime is 21655610407. The next prime is 21655610441. The reversal of 21655610416 is 61401655612.

It is a Harshad number since it is a multiple of its sum of digits (37).

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 15 ways as a sum of consecutive naturals, for example, 2607166 + ... + 2615458.

Almost surely, 2^21655610416 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 21655610416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23566040784).

21655610416 is an abundant number, since it is smaller than the sum of its proper divisors (25476471152).

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

21655610416 is a wasteful number, since it uses less digits than its factorization.

21655610416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8750 (or 8744 counting only the distinct ones).

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

The spelling of 21655610416 in words is "twenty-one billion, six hundred fifty-five million, six hundred ten thousand, four hundred sixteen".