21637449943 has 2 divisors, whose sum is σ = 21637449944. Its totient is φ = 21637449942.

The previous prime is 21637449937. The next prime is 21637449961. The reversal of 21637449943 is 34994473612.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21637449943 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21637449143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10818724971 + 10818724972.

It is an arithmetic number, because the mean of its divisors is an integer number (10818724972).

Almost surely, 2^21637449943 is an apocalyptic number.

21637449943 is a deficient number, since it is larger than the sum of its proper divisors (1).

21637449943 is an equidigital number, since it uses as much as digits as its factorization.

21637449943 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3919104, while the sum is 52.

The spelling of 21637449943 in words is "twenty-one billion, six hundred thirty-seven million, four hundred forty-nine thousand, nine hundred forty-three".