21979978344 has 128 divisors (see below), whose sum is σ = 61883827200. Its totient is φ = 7227817920.

The previous prime is 21979978337. The next prime is 21979978357. The reversal of 21979978344 is 44387997912.

21979978344 is a `hidden beast` number, since 219 + 7 + 9 + 9 + 78 + 344 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6294439 + ... + 6297929.

It is an arithmetic number, because the mean of its divisors is an integer number (483467400).

Almost surely, 2^21979978344 is an apocalyptic number.

21979978344 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21979978344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30941913600).

21979978344 is an abundant number, since it is smaller than the sum of its proper divisors (39903848856).

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

21979978344 is a wasteful number, since it uses less digits than its factorization.

21979978344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3892 (or 3882 counting only the distinct ones).

The product of its digits is 27433728, while the sum is 63.

The spelling of 21979978344 in words is "twenty-one billion, nine hundred seventy-nine million, nine hundred seventy-eight thousand, three hundred forty-four".