20951640 has 48 divisors (see below), whose sum is σ = 68094000. Its totient is φ = 5587008.

The previous prime is 20951617. The next prime is 20951647. The reversal of 20951640 is 4615902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20951647) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 28740 + ... + 29459.

It is an arithmetic number, because the mean of its divisors is an integer number (1418625).

Almost surely, 2^20951640 is an apocalyptic number.

20951640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20951640 is an abundant number, since it is smaller than the sum of its proper divisors (47142360).

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

20951640 is a wasteful number, since it uses less digits than its factorization.

20951640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58216 (or 58209 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 20951640 is about 4577.2961451058. The cubic root of 20951640 is about 275.6804745884.

The spelling of 20951640 in words is "twenty million, nine hundred fifty-one thousand, six hundred forty".