20643968 has 16 divisors (see below), whose sum is σ = 41126910. Its totient is φ = 10321920.

The previous prime is 20643947. The next prime is 20644003. The reversal of 20643968 is 86934602.

It can be written as a sum of positive squares in only one way, i.e., 18593344 + 2050624 = 4312^2 + 1432^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80513 + ... + 80768.

Almost surely, 2^20643968 is an apocalyptic number.

It is an amenable number.

20643968 is a deficient number, since it is larger than the sum of its proper divisors (20482942).

20643968 is an equidigital number, since it uses as much as digits as its factorization.

20643968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161295 (or 161283 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 38.

The square root of 20643968 is about 4543.5633593029. The cubic root of 20643968 is about 274.3243712050.

The spelling of 20643968 in words is "twenty million, six hundred forty-three thousand, nine hundred sixty-eight".