20780864 has 28 divisors (see below), whose sum is σ = 44410884. Its totient is φ = 9590784.

The previous prime is 20780863. The next prime is 20780869. The reversal of 20780864 is 46808702.

It can be written as a sum of positive squares in 2 ways, for example, as 1420864 + 19360000 = 1192^2 + 4400^2 .

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20780863) 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 3 ways as a sum of consecutive naturals, for example, 11657 + ... + 13320.

It is an arithmetic number, because the mean of its divisors is an integer number (1586103).

Almost surely, 2^20780864 is an apocalyptic number.

It is an amenable number.

20780864 is an abundant number, since it is smaller than the sum of its proper divisors (23630020).

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

20780864 is a wasteful number, since it uses less digits than its factorization.

20780864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25002 (or 24992 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 35.

The square root of 20780864 is about 4558.6032948700. The cubic root of 20780864 is about 274.9294099809.

The spelling of 20780864 in words is "twenty million, seven hundred eighty thousand, eight hundred sixty-four".