18561009966405 has 32 divisors (see below), whose sum is σ = 30022164483840. Its totient is φ = 9791221900800.

The previous prime is 18561009966397. The next prime is 18561009966413. The reversal of 18561009966405 is 50466990016581.

It is an interprime number because it is at equal distance from previous prime (18561009966397) and next prime (18561009966413).

It is not a de Polignac number, because 18561009966405 - 2³ = 18561009966397 is a prime.

It is a super-2 number, since 2×18561009966405² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4742440 + ... + 7720929.

It is an arithmetic number, because the mean of its divisors is an integer number (938192640120).

Almost surely, 2^{18561009966405} is an apocalyptic number.

18561009966405 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18561009966405 is a deficient number, since it is larger than the sum of its proper divisors (11461154517435).

18561009966405 is a wasteful number, since it uses less digits than its factorization.

18561009966405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12464461.

The product of its (nonzero) digits is 13996800, while the sum is 60.

The spelling of 18561009966405 in words is "eighteen trillion, five hundred sixty-one billion, nine million, nine hundred sixty-six thousand, four hundred five".