20813904 has 30 divisors (see below), whose sum is σ = 58250426. Its totient is φ = 6937920.

The previous prime is 20813887. The next prime is 20813921. The reversal of 20813904 is 40931802.

It is an interprime number because it is at equal distance from previous prime (20813887) and next prime (20813921).

It can be written as a sum of positive squares in only one way, i.e., 20684304 + 129600 = 4548^2 + 360^2 .

It is a congruent number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 72127 + ... + 72414.

Almost surely, 2^20813904 is an apocalyptic number.

20813904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

20813904 is an abundant number, since it is smaller than the sum of its proper divisors (37436522).

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

20813904 is a wasteful number, since it uses less digits than its factorization.

20813904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144555 (or 144546 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 20813904 is about 4562.2257725807. The cubic root of 20813904 is about 275.0750384758.

The spelling of 20813904 in words is "twenty million, eight hundred thirteen thousand, nine hundred four".