161015055561 has 6 divisors (see below), whose sum is σ = 232577302490. Its totient is φ = 107343370368.

The previous prime is 161015055559. The next prime is 161015055577. The reversal of 161015055561 is 165550510161.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 118818090000 + 42196965561 = 344700^2 + 205419^2 .

It is not a de Polignac number, because 161015055561 - 2¹ = 161015055559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161015050561) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8945280856 + ... + 8945280873.

Almost surely, 2^161015055561 is an apocalyptic number.

It is an amenable number.

161015055561 is a deficient number, since it is larger than the sum of its proper divisors (71562246929).

161015055561 is a wasteful number, since it uses less digits than its factorization.

161015055561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17890561735 (or 17890561732 counting only the distinct ones).

The product of its (nonzero) digits is 22500, while the sum is 36.

The spelling of 161015055561 in words is "one hundred sixty-one billion, fifteen million, fifty-five thousand, five hundred sixty-one".