18440536637 has 2 divisors, whose sum is σ = 18440536638. Its totient is φ = 18440536636.

The previous prime is 18440536601. The next prime is 18440536717. The reversal of 18440536637 is 73663504481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14967320281 + 3473216356 = 122341^2 + 58934^2 .

It is a cyclic number.

It is not a de Polignac number, because 18440536637 - 2³⁰ = 17366794813 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18440536591 and 18440536600.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18440556637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9220268318 + 9220268319.

It is an arithmetic number, because the mean of its divisors is an integer number (9220268319).

Almost surely, 2^18440536637 is an apocalyptic number.

It is an amenable number.

18440536637 is a deficient number, since it is larger than the sum of its proper divisors (1).

18440536637 is an equidigital number, since it uses as much as digits as its factorization.

18440536637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1451520, while the sum is 47.

The spelling of 18440536637 in words is "eighteen billion, four hundred forty million, five hundred thirty-six thousand, six hundred thirty-seven".