20918780 has 24 divisors (see below), whose sum is σ = 44068752. Its totient is φ = 8340992.

The previous prime is 20918771. The next prime is 20918783. The reversal of 20918780 is 8781902.

It is a happy number.

It is a plaindrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 20918780.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20918783) 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, 5579 + ... + 8541.

It is an arithmetic number, because the mean of its divisors is an integer number (1836198).

Almost surely, 2^20918780 is an apocalyptic number.

20918780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20918780 is an abundant number, since it is smaller than the sum of its proper divisors (23149972).

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

20918780 is a wasteful number, since it uses less digits than its factorization.

20918780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3325 (or 3323 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 20918780 is about 4573.7052812791. The cubic root of 20918780 is about 275.5362758460.

The spelling of 20918780 in words is "twenty million, nine hundred eighteen thousand, seven hundred eighty".