161511105561 has 8 divisors (see below), whose sum is σ = 231913382400. Its totient is φ = 99391449552.

The previous prime is 161511105551. The next prime is 161511105571. The reversal of 161511105561 is 165501115161.

It is an interprime number because it is at equal distance from previous prime (161511105551) and next prime (161511105571).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 161511105561 - 2⁵ = 161511105529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161511105551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2070655161 + ... + 2070655238.

It is an arithmetic number, because the mean of its divisors is an integer number (28989172800).

Almost surely, 2^161511105561 is an apocalyptic number.

It is an amenable number.

161511105561 is a deficient number, since it is larger than the sum of its proper divisors (70402276839).

161511105561 is a wasteful number, since it uses less digits than its factorization.

161511105561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4141310415.

The product of its (nonzero) digits is 4500, while the sum is 33.

The spelling of 161511105561 in words is "one hundred sixty-one billion, five hundred eleven million, one hundred five thousand, five hundred sixty-one".