21979764720 has 100 divisors (see below), whose sum is σ = 76339001640. Its totient is φ = 5861268864.

The previous prime is 21979764707. The next prime is 21979764727. The reversal of 21979764720 is 2746797912.

It is a super-2 number, since 2×21979764720² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21979764727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1689490 + ... + 1702449.

Almost surely, 2^21979764720 is an apocalyptic number.

21979764720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21979764720 is an abundant number, since it is smaller than the sum of its proper divisors (54359236920).

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

21979764720 is a wasteful number, since it uses less digits than its factorization.

21979764720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3391964 (or 3391949 counting only the distinct ones).

The product of its (nonzero) digits is 2667168, while the sum is 54.

The spelling of 21979764720 in words is "twenty-one billion, nine hundred seventy-nine million, seven hundred sixty-four thousand, seven hundred twenty".