161616610111561 has 8 divisors (see below), whose sum is σ = 176311402496064. Its totient is φ = 146922213274320.

The previous prime is 161616610111513. The next prime is 161616610111571. The reversal of 161616610111561 is 165111016616161.

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

It is not a de Polignac number, because 161616610111561 - 2²¹ = 161616608014409 is a prime.

It is a super-2 number, since 2×161616610111561² (a number of 29 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161616610111571) 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, 98032165 + ... + 99667138.

It is an arithmetic number, because the mean of its divisors is an integer number (22038925312008).

Almost surely, 2^{161616610111561} is an apocalyptic number.

161616610111561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

161616610111561 is a deficient number, since it is larger than the sum of its proper divisors (14694792384503).

161616610111561 is a wasteful number, since it uses less digits than its factorization.

161616610111561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197773631.

The product of its (nonzero) digits is 38880, while the sum is 43.

The spelling of 161616610111561 in words is "one hundred sixty-one trillion, six hundred sixteen billion, six hundred ten million, one hundred eleven thousand, five hundred sixty-one".