20655780 has 24 divisors (see below), whose sum is σ = 57836352. Its totient is φ = 5508192.

The previous prime is 20655773. The next prime is 20655829. The reversal of 20655780 is 8755602.

It is a happy number.

It is a super-2 number, since 2×20655780² = 853322494816800, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 172072 + ... + 172191.

It is an arithmetic number, because the mean of its divisors is an integer number (2409848).

Almost surely, 2^20655780 is an apocalyptic number.

20655780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20655780 is an abundant number, since it is smaller than the sum of its proper divisors (37180572).

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

20655780 is a wasteful number, since it uses less digits than its factorization.

20655780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 344275 (or 344273 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 33.

The square root of 20655780 is about 4544.8630342399. The cubic root of 20655780 is about 274.3766819116.

The spelling of 20655780 in words is "twenty million, six hundred fifty-five thousand, seven hundred eighty".