21531204490643 has 2 divisors, whose sum is σ = 21531204490644. Its totient is φ = 21531204490642.

The previous prime is 21531204490589. The next prime is 21531204490661. The reversal of 21531204490643 is 34609440213512.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21531204490643 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 21531204490594 and 21531204490603.

It is not a weakly prime, because it can be changed into another prime (21531204690643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765602245321 + 10765602245322.

It is an arithmetic number, because the mean of its divisors is an integer number (10765602245322).

Almost surely, 2^{21531204490643} is an apocalyptic number.

21531204490643 is a deficient number, since it is larger than the sum of its proper divisors (1).

21531204490643 is an equidigital number, since it uses as much as digits as its factorization.

21531204490643 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 622080, while the sum is 44.

The spelling of 21531204490643 in words is "twenty-one trillion, five hundred thirty-one billion, two hundred four million, four hundred ninety thousand, six hundred forty-three".