20978660 has 24 divisors (see below), whose sum is σ = 46374720. Its totient is φ = 7949664.

The previous prime is 20978623. The next prime is 20978669. The reversal of 20978660 is 6687902.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (38).

It is not an unprimeable number, because it can be changed into a prime (20978669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27224 + ... + 27983.

It is an arithmetic number, because the mean of its divisors is an integer number (1932280).

Almost surely, 2^20978660 is an apocalyptic number.

20978660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20978660 is an abundant number, since it is smaller than the sum of its proper divisors (25396060).

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

20978660 is a wasteful number, since it uses less digits than its factorization.

20978660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55235 (or 55233 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 38.

The square root of 20978660 is about 4580.2467182456. The cubic root of 20978660 is about 275.7989328824.

The spelling of 20978660 in words is "twenty million, nine hundred seventy-eight thousand, six hundred sixty".