161561550161661 has 32 divisors (see below), whose sum is σ = 242187026928000. Its totient is φ = 95113450430208.

The previous prime is 161561550161653. The next prime is 161561550161701. The reversal of 161561550161661 is 166161055165161.

It is not a de Polignac number, because 161561550161661 - 2³ = 161561550161653 is a prime.

It is a super-2 number, since 2×161561550161661² (a number of 29 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161561550161611) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 655144651 + ... + 655391208.

It is an arithmetic number, because the mean of its divisors is an integer number (7568344591500).

Almost surely, 2^{161561550161661} is an apocalyptic number.

It is an amenable number.

161561550161661 is a deficient number, since it is larger than the sum of its proper divisors (80625476766339).

161561550161661 is a wasteful number, since it uses less digits than its factorization.

161561550161661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1310536013.

The product of its (nonzero) digits is 972000, while the sum is 51.

The spelling of 161561550161661 in words is "one hundred sixty-one trillion, five hundred sixty-one billion, five hundred fifty million, one hundred sixty-one thousand, six hundred sixty-one".