21531443643 has 6 divisors (see below), whose sum is σ = 31100974164. Its totient is φ = 14354295756.

The previous prime is 21531443627. The next prime is 21531443699. The reversal of 21531443643 is 34634413512.

21531443643 is a `hidden beast` number, since 2 + 1 + 5 + 3 + 1 + 4 + 4 + 3 + 643 = 666.

It is not a de Polignac number, because 21531443643 - 2⁴ = 21531443627 is a prime.

It is a super-2 number, since 2×21531443643² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21531443598 and 21531443607.

It is not an unprimeable number, because it can be changed into a prime (21531543643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1196191305 + ... + 1196191322.

It is an arithmetic number, because the mean of its divisors is an integer number (5183495694).

Almost surely, 2^21531443643 is an apocalyptic number.

21531443643 is a deficient number, since it is larger than the sum of its proper divisors (9569530521).

21531443643 is a wasteful number, since it uses less digits than its factorization.

21531443643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2392382633 (or 2392382630 counting only the distinct ones).

The product of its digits is 103680, while the sum is 36.

The spelling of 21531443643 in words is "twenty-one billion, five hundred thirty-one million, four hundred forty-three thousand, six hundred forty-three".