20813906 has 16 divisors (see below), whose sum is σ = 32512344. Its totient is φ = 9984384.

The previous prime is 20813887. The next prime is 20813921. The reversal of 20813906 is 60931802.

It can be written as a sum of positive squares in 4 ways, for example, as 19882681 + 931225 = 4459^2 + 965^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3476 + ... + 7328.

Almost surely, 2^20813906 is an apocalyptic number.

20813906 is a deficient number, since it is larger than the sum of its proper divisors (11698438).

20813906 is a wasteful number, since it uses less digits than its factorization.

20813906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3965.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 20813906 is about 4562.2259917720. The cubic root of 20813906 is about 275.0750472864.

The spelling of 20813906 in words is "twenty million, eight hundred thirteen thousand, nine hundred six".