21366510016 has 56 divisors (see below), whose sum is σ = 43131882240. Its totient is φ = 10498944000.

The previous prime is 21366510013. The next prime is 21366510017. The reversal of 21366510016 is 61001566312.

It is a self number, because there is not a number n which added to its sum of digits gives 21366510016.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21366510013) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7420065 + ... + 7422943.

Almost surely, 2^21366510016 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 21366510016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21565941120).

21366510016 is an abundant number, since it is smaller than the sum of its proper divisors (21765372224).

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

21366510016 is a wasteful number, since it uses less digits than its factorization.

21366510016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4853 (or 4843 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 31.

The spelling of 21366510016 in words is "twenty-one billion, three hundred sixty-six million, five hundred ten thousand, sixteen".