20979780 has 24 divisors (see below), whose sum is σ = 58743552. Its totient is φ = 5594592.

The previous prime is 20979779. The next prime is 20979799. The reversal of 20979780 is 8797902.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 174772 + ... + 174891.

It is an arithmetic number, because the mean of its divisors is an integer number (2447648).

Almost surely, 2^20979780 is an apocalyptic number.

20979780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20979780 is an abundant number, since it is smaller than the sum of its proper divisors (37763772).

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

20979780 is a wasteful number, since it uses less digits than its factorization.

20979780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 349675 (or 349673 counting only the distinct ones).

The product of its (nonzero) digits is 63504, while the sum is 42.

The square root of 20979780 is about 4580.3689807700. The cubic root of 20979780 is about 275.8038408748.

The spelling of 20979780 in words is "twenty million, nine hundred seventy-nine thousand, seven hundred eighty".