21036991680 has 112 divisors (see below), whose sum is σ = 74213862240. Its totient is φ = 5609862144.

The previous prime is 21036991669. The next prime is 21036991681. The reversal of 21036991680 is 8619963012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21036991681) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1208779 + ... + 1226058.

It is an arithmetic number, because the mean of its divisors is an integer number (662623770).

Almost surely, 2^21036991680 is an apocalyptic number.

21036991680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21036991680 is an abundant number, since it is smaller than the sum of its proper divisors (53176870560).

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

21036991680 is a wasteful number, since it uses less digits than its factorization.

21036991680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2434863 (or 2434847 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 45.

The spelling of 21036991680 in words is "twenty-one billion, thirty-six million, nine hundred ninety-one thousand, six hundred eighty".