161651791 has 16 divisors (see below), whose sum is σ = 194997760. Its totient is φ = 130908960.

The previous prime is 161651767. The next prime is 161651801. The reversal of 161651791 is 197156161.

161651791 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 161651791 - 2²³ = 153263183 is a prime.

It is a super-2 number, since 2×161651791² = 52262603067015362, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161651791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161651741) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 54550 + ... + 57436.

It is an arithmetic number, because the mean of its divisors is an integer number (12187360).

Almost surely, 2^161651791 is an apocalyptic number.

161651791 is a deficient number, since it is larger than the sum of its proper divisors (33345969).

161651791 is a wasteful number, since it uses less digits than its factorization.

161651791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3334.

The product of its digits is 11340, while the sum is 37.

The square root of 161651791 is about 12714.2357615391. The cubic root of 161651791 is about 544.7453188186.

It can be divided in two parts, 16165 and 1791, that added together give a square (17956 = 134²).

The spelling of 161651791 in words is "one hundred sixty-one million, six hundred fifty-one thousand, seven hundred ninety-one".