20637864 has 96 divisors (see below), whose sum is σ = 63783720. Its totient is φ = 5971968.

The previous prime is 20637863. The next prime is 20637887. The reversal of 20637864 is 46873602.

It can be written as a sum of positive squares in 4 ways, for example, as 20520900 + 116964 = 4530^2 + 342^2 .

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

It is not an unprimeable number, because it can be changed into a prime (20637863) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15264 + ... + 16560.

Almost surely, 2^20637864 is an apocalyptic number.

20637864 is a gapful number since it is divisible by the number (24) 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 20637864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31891860).

20637864 is an abundant number, since it is smaller than the sum of its proper divisors (43145856).

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

20637864 is a wasteful number, since it uses less digits than its factorization.

20637864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1339 (or 1332 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 36.

The square root of 20637864 is about 4542.8915901659. The cubic root of 20637864 is about 274.2973311672.

The spelling of 20637864 in words is "twenty million, six hundred thirty-seven thousand, eight hundred sixty-four".