20397664 has 48 divisors (see below), whose sum is σ = 47035296. Its totient is φ = 8524800.

The previous prime is 20397647. The next prime is 20397673. The reversal of 20397664 is 46679302.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8074 + ... + 10294.

It is an arithmetic number, because the mean of its divisors is an integer number (979902).

Almost surely, 2^20397664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20397664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23517648).

20397664 is an abundant number, since it is smaller than the sum of its proper divisors (26637632).

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

20397664 is a wasteful number, since it uses less digits than its factorization.

20397664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2279 (or 2271 counting only the distinct ones).

The product of its (nonzero) digits is 54432, while the sum is 37.

The square root of 20397664 is about 4516.3773093044. The cubic root of 20397664 is about 273.2290116797.

The spelling of 20397664 in words is "twenty million, three hundred ninety-seven thousand, six hundred sixty-four".