20904660 has 144 divisors (see below), whose sum is σ = 74221056. Its totient is φ = 4663296.

The previous prime is 20904649. The next prime is 20904673. The reversal of 20904660 is 6640902.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 59044 + ... + 59396.

It is an arithmetic number, because the mean of its divisors is an integer number (515424).

Almost surely, 2^20904660 is an apocalyptic number.

20904660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20904660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37110528).

20904660 is an abundant number, since it is smaller than the sum of its proper divisors (53316396).

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

20904660 is a wasteful number, since it uses less digits than its factorization.

20904660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422 (or 417 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 20904660 is about 4572.1614144735. The cubic root of 20904660 is about 275.4742670049.

The spelling of 20904660 in words is "twenty million, nine hundred four thousand, six hundred sixty".