20840664 has 32 divisors (see below), whose sum is σ = 56110320. Its totient is φ = 6412416.

The previous prime is 20840653. The next prime is 20840683. The reversal of 20840664 is 46604802.

It is a congruent number.

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, 33087 + ... + 33710.

Almost surely, 2^20840664 is an apocalyptic number.

20840664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

20840664 is an abundant number, since it is smaller than the sum of its proper divisors (35269656).

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

20840664 is a wasteful number, since it uses less digits than its factorization.

20840664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66819 (or 66815 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

The square root of 20840664 is about 4565.1576095465. The cubic root of 20840664 is about 275.1928740606.

The spelling of 20840664 in words is "twenty million, eight hundred forty thousand, six hundred sixty-four".