20400765 has 64 divisors (see below), whose sum is σ = 43130880. Its totient is φ = 7971840.

The previous prime is 20400719. The next prime is 20400803. The reversal of 20400765 is 56700402.

It is a happy number.

It is not a de Polignac number, because 20400765 - 2⁷ = 20400637 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 19116 + ... + 20154.

It is an arithmetic number, because the mean of its divisors is an integer number (673920).

Almost surely, 2^20400765 is an apocalyptic number.

It is an amenable number.

20400765 is an abundant number, since it is smaller than the sum of its proper divisors (22730115).

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

20400765 is a wasteful number, since it uses less digits than its factorization.

20400765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1082.

The product of its (nonzero) digits is 1680, while the sum is 24.

The square root of 20400765 is about 4516.7206023840. The cubic root of 20400765 is about 273.2428570598.

The spelling of 20400765 in words is "twenty million, four hundred thousand, seven hundred sixty-five".