20643688 has 24 divisors (see below), whose sum is σ = 41916150. Its totient is φ = 9527232.

The previous prime is 20643683. The next prime is 20643697. The reversal of 20643688 is 88634602.

It can be written as a sum of positive squares in 3 ways, for example, as 9872164 + 10771524 = 3142^2 + 3282^2 .

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (20643683) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6283 + ... + 8986.

Almost surely, 2^20643688 is an apocalyptic number.

It is an amenable number.

20643688 is an abundant number, since it is smaller than the sum of its proper divisors (21272462).

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

20643688 is a wasteful number, since it uses less digits than its factorization.

20643688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15301 (or 15284 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 37.

The square root of 20643688 is about 4543.5325463784. The cubic root of 20643688 is about 274.3231309530.

The spelling of 20643688 in words is "twenty million, six hundred forty-three thousand, six hundred eighty-eight".