161555501661 has 8 divisors (see below), whose sum is σ = 216728853600. Its totient is φ = 107042908752.

The previous prime is 161555501621. The next prime is 161555501669. The reversal of 161555501661 is 166105555161.

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

It is not a de Polignac number, because 161555501661 - 2⁷ = 161555501533 is a prime.

It is a super-2 number, since 2×161555501661² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161555501669) 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, 165189186 + ... + 165190163.

It is an arithmetic number, because the mean of its divisors is an integer number (27091106700).

Almost surely, 2^161555501661 is an apocalyptic number.

It is an amenable number.

161555501661 is a deficient number, since it is larger than the sum of its proper divisors (55173351939).

161555501661 is a wasteful number, since it uses less digits than its factorization.

161555501661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330379515.

The product of its (nonzero) digits is 135000, while the sum is 42.

The spelling of 161555501661 in words is "one hundred sixty-one billion, five hundred fifty-five million, five hundred one thousand, six hundred sixty-one".