21403444637 has 2 divisors, whose sum is σ = 21403444638. Its totient is φ = 21403444636.

The previous prime is 21403444631. The next prime is 21403444663. The reversal of 21403444637 is 73644430412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14345092441 + 7058352196 = 119771^2 + 84014^2 .

It is a cyclic number.

It is not a de Polignac number, because 21403444637 - 2²² = 21399250333 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21403444637.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21403444631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701722318 + 10701722319.

It is an arithmetic number, because the mean of its divisors is an integer number (10701722319).

Almost surely, 2^21403444637 is an apocalyptic number.

It is an amenable number.

21403444637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21403444637 is an equidigital number, since it uses as much as digits as its factorization.

21403444637 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 193536, while the sum is 38.

The spelling of 21403444637 in words is "twenty-one billion, four hundred three million, four hundred forty-four thousand, six hundred thirty-seven".