20901640 has 16 divisors (see below), whose sum is σ = 47028780. Its totient is φ = 8360640.

The previous prime is 20901637. The next prime is 20901667. The reversal of 20901640 is 4610902.

It can be written as a sum of positive squares in 2 ways, for example, as 19945156 + 956484 = 4466^2 + 978^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 261231 + ... + 261310.

Almost surely, 2^20901640 is an apocalyptic number.

20901640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20901640 is an abundant number, since it is smaller than the sum of its proper divisors (26127140).

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

20901640 is a wasteful number, since it uses less digits than its factorization.

20901640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 522552 (or 522548 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 20901640 is about 4571.8311429886. The cubic root of 20901640 is about 275.4610008663.

The spelling of 20901640 in words is "twenty million, nine hundred one thousand, six hundred forty".