161995331 has 4 divisors (see below), whose sum is σ = 163429032. Its totient is φ = 160561632.

The previous prime is 161995307. The next prime is 161995373. The reversal of 161995331 is 133599161.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 161995331 - 2¹⁰ = 161994307 is a prime.

It is a super-2 number, since 2×161995331² = 52484974531599122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161995381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 716681 + ... + 716906.

It is an arithmetic number, because the mean of its divisors is an integer number (40857258).

Almost surely, 2^161995331 is an apocalyptic number.

161995331 is a deficient number, since it is larger than the sum of its proper divisors (1433701).

161995331 is a wasteful number, since it uses less digits than its factorization.

161995331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1433700.

The product of its digits is 21870, while the sum is 38.

The square root of 161995331 is about 12727.7386443940. The cubic root of 161995331 is about 545.1309406783.

The spelling of 161995331 in words is "one hundred sixty-one million, nine hundred ninety-five thousand, three hundred thirty-one".