21044651643 has 6 divisors (see below), whose sum is σ = 30397830164. Its totient is φ = 14029767756.

The previous prime is 21044651603. The next prime is 21044651669. The reversal of 21044651643 is 34615644012.

21044651643 is a `hidden beast` number, since 2 + 1 + 0 + 4 + 4 + 6 + 5 + 1 + 643 = 666.

It is not a de Polignac number, because 21044651643 - 2¹⁰ = 21044650619 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21044651598 and 21044651607.

It is not an unprimeable number, because it can be changed into a prime (21044651603) 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, 1169147305 + ... + 1169147322.

Almost surely, 2^21044651643 is an apocalyptic number.

21044651643 is a deficient number, since it is larger than the sum of its proper divisors (9353178521).

21044651643 is a wasteful number, since it uses less digits than its factorization.

21044651643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2338294633 (or 2338294630 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The spelling of 21044651643 in words is "twenty-one billion, forty-four million, six hundred fifty-one thousand, six hundred forty-three".