20890640 has 40 divisors (see below), whose sum is σ = 48830208. Its totient is φ = 8311680.

The previous prime is 20890619. The next prime is 20890663. The reversal of 20890640 is 4609802.

It is a tau number, because it is divible by the number of its divisors (40).

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, 17255 + ... + 18425.

Almost surely, 2^20890640 is an apocalyptic number.

20890640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20890640 is an abundant number, since it is smaller than the sum of its proper divisors (27939568).

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

20890640 is a wasteful number, since it uses less digits than its factorization.

20890640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1407 (or 1401 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 20890640 is about 4570.6279656082. The cubic root of 20890640 is about 275.4126696873.

The spelling of 20890640 in words is "twenty million, eight hundred ninety thousand, six hundred forty".