20643944 has 8 divisors (see below), whose sum is σ = 38707410. Its totient is φ = 10321968.

The previous prime is 20643943. The next prime is 20643947. The reversal of 20643944 is 44934602.

It can be written as a sum of positive squares in only one way, i.e., 18576100 + 2067844 = 4310^2 + 1438^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a self number, because there is not a number n which added to its sum of digits gives 20643944.

It is not an unprimeable number, because it can be changed into a prime (20643941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1290239 + ... + 1290254.

Almost surely, 2^20643944 is an apocalyptic number.

It is an amenable number.

20643944 is a deficient number, since it is larger than the sum of its proper divisors (18063466).

20643944 is a wasteful number, since it uses less digits than its factorization.

20643944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2580499 (or 2580495 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 32.

The square root of 20643944 is about 4543.5607182033. The cubic root of 20643944 is about 274.3242648981.

The spelling of 20643944 in words is "twenty million, six hundred forty-three thousand, nine hundred forty-four".