21651625016 has 64 divisors (see below), whose sum is σ = 47164481280. Its totient is φ = 9126639360.

The previous prime is 21651625007. The next prime is 21651625033. The reversal of 21651625016 is 61052615612.

It is a congruent number.

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, 1044836 + ... + 1065356.

It is an arithmetic number, because the mean of its divisors is an integer number (736945020).

Almost surely, 2^21651625016 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 21651625016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23582240640).

21651625016 is an abundant number, since it is smaller than the sum of its proper divisors (25512856264).

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

21651625016 is a wasteful number, since it uses less digits than its factorization.

21651625016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20844 (or 20840 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 35.

The spelling of 21651625016 in words is "twenty-one billion, six hundred fifty-one million, six hundred twenty-five thousand, sixteen".