20945664 has 54 divisors (see below), whose sum is σ = 60398156. Its totient is φ = 6981120.

The previous prime is 20945651. The next prime is 20945693. The reversal of 20945664 is 46654902.

20945664 is a `hidden beast` number, since 2 + 0 + 94 + 566 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2242 + ... + 6849.

Almost surely, 2^20945664 is an apocalyptic number.

20945664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

20945664 is an abundant number, since it is smaller than the sum of its proper divisors (39452492).

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

20945664 is an equidigital number, since it uses as much as digits as its factorization.

20945664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9113 (or 9096 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 20945664 is about 4576.6433114238. The cubic root of 20945664 is about 275.6542614745.

It can be divided in two parts, 20945 and 664, that added together give a square (21609 = 147²).

The spelling of 20945664 in words is "twenty million, nine hundred forty-five thousand, six hundred sixty-four".