20900640 has 48 divisors (see below), whose sum is σ = 65838528. Its totient is φ = 5573376.

The previous prime is 20900609. The next prime is 20900653. The reversal of 20900640 is 4600902.

It is a tau number, because it is divible by the number of its divisors (48).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21292 + ... + 22251.

It is an arithmetic number, because the mean of its divisors is an integer number (1371636).

Almost surely, 2^20900640 is an apocalyptic number.

20900640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20900640 is an abundant number, since it is smaller than the sum of its proper divisors (44937888).

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

20900640 is a wasteful number, since it uses less digits than its factorization.

20900640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43561 (or 43553 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 20900640 is about 4571.7217763114. The cubic root of 20900640 is about 275.4566078236.

The spelling of 20900640 in words is "twenty million, nine hundred thousand, six hundred forty".