161121686409 has 64 divisors (see below), whose sum is σ = 252908409600. Its totient is φ = 101204038656.

The previous prime is 161121686333. The next prime is 161121686431. The reversal of 161121686409 is 904686121161.

161121686409 is a `hidden beast` number, since 1 + 61 + 121 + 68 + 6 + 409 = 666.

It is not a de Polignac number, because 161121686409 - 2²⁵ = 161088131977 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161121686009) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 59828467 + ... + 59831159.

It is an arithmetic number, because the mean of its divisors is an integer number (3951693900).

Almost surely, 2^161121686409 is an apocalyptic number.

It is an amenable number.

161121686409 is a deficient number, since it is larger than the sum of its proper divisors (91786723191).

161121686409 is a wasteful number, since it uses less digits than its factorization.

161121686409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4551 (or 4545 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The spelling of 161121686409 in words is "one hundred sixty-one billion, one hundred twenty-one million, six hundred eighty-six thousand, four hundred nine".