21644496371 has 2 divisors, whose sum is σ = 21644496372. Its totient is φ = 21644496370.

The previous prime is 21644496301. The next prime is 21644496397. The reversal of 21644496371 is 17369444612.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21644496371 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21644496301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10822248185 + 10822248186.

It is an arithmetic number, because the mean of its divisors is an integer number (10822248186).

Almost surely, 2^21644496371 is an apocalyptic number.

21644496371 is a deficient number, since it is larger than the sum of its proper divisors (1).

21644496371 is an equidigital number, since it uses as much as digits as its factorization.

21644496371 is an evil number, because the sum of its binary digits is even.

The product of its digits is 870912, while the sum is 47.

The spelling of 21644496371 in words is "twenty-one billion, six hundred forty-four million, four hundred ninety-six thousand, three hundred seventy-one".