21120019979 has 16 divisors (see below), whose sum is σ = 22316692320. Its totient is φ = 19956518400.

The previous prime is 21120019961. The next prime is 21120020029. The reversal of 21120019979 is 97991002112.

It is a cyclic number.

It is not a de Polignac number, because 21120019979 - 2¹² = 21120015883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21120019919) 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, 599204 + ... + 633470.

It is an arithmetic number, because the mean of its divisors is an integer number (1394793270).

Almost surely, 2^21120019979 is an apocalyptic number.

21120019979 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21120019979 is a deficient number, since it is larger than the sum of its proper divisors (1196672341).

21120019979 is a wasteful number, since it uses less digits than its factorization.

21120019979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34750.

The product of its (nonzero) digits is 20412, while the sum is 41.

The spelling of 21120019979 in words is "twenty-one billion, one hundred twenty million, nineteen thousand, nine hundred seventy-nine".