20979940 has 24 divisors (see below), whose sum is σ = 44356032. Its totient is φ = 8335200.

The previous prime is 20979929. The next prime is 20979943. The reversal of 20979940 is 4997902.

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 20979893 and 20979902.

It is not an unprimeable number, because it can be changed into a prime (20979943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 454 + ... + 6493.

It is an arithmetic number, because the mean of its divisors is an integer number (1848168).

Almost surely, 2^20979940 is an apocalyptic number.

20979940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20979940 is an abundant number, since it is smaller than the sum of its proper divisors (23376092).

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

20979940 is a wasteful number, since it uses less digits than its factorization.

20979940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7107 (or 7105 counting only the distinct ones).

The product of its (nonzero) digits is 40824, while the sum is 40.

The square root of 20979940 is about 4580.3864465785. The cubic root of 20979940 is about 275.8045420023.

The spelling of 20979940 in words is "twenty million, nine hundred seventy-nine thousand, nine hundred forty".