20978680 has 32 divisors (see below), whose sum is σ = 49980240. Its totient is φ = 7897600.

The previous prime is 20978677. The next prime is 20978681. The reversal of 20978680 is 8687902.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20978681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14746 + ... + 16105.

Almost surely, 2^20978680 is an apocalyptic number.

20978680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20978680 is an abundant number, since it is smaller than the sum of its proper divisors (29001560).

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

20978680 is a wasteful number, since it uses less digits than its factorization.

20978680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30879 (or 30875 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 40.

The square root of 20978680 is about 4580.2489015336. The cubic root of 20978680 is about 275.7990205267.

The spelling of 20978680 in words is "twenty million, nine hundred seventy-eight thousand, six hundred eighty".