18917867549405 has 54 divisors (see below), whose sum is σ = 25226559197658. Its totient is φ = 13609140103680.

The previous prime is 18917867549369. The next prime is 18917867549437. The reversal of 18917867549405 is 50494576871981.

It can be written as a sum of positive squares in 3 ways, for example, as 1352741129476 + 17565126419929 = 1163074^2 + 4191077^2 .

It is not a de Polignac number, because 18917867549405 - 2³² = 18913572582109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 10377326324 + ... + 10377328146.

Almost surely, 2^{18917867549405} is an apocalyptic number.

It is an amenable number.

18917867549405 is a deficient number, since it is larger than the sum of its proper divisors (6308691648253).

18917867549405 is an frugal number, since it uses more digits than its factorization.

18917867549405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3867 (or 1936 counting only the distinct ones).

The product of its (nonzero) digits is 609638400, while the sum is 74.

The spelling of 18917867549405 in words is "eighteen trillion, nine hundred seventeen billion, eight hundred sixty-seven million, five hundred forty-nine thousand, four hundred five".