161191271720 has 32 divisors (see below), whose sum is σ = 362700416520. Its totient is φ = 64472943360.

The previous prime is 161191271701. The next prime is 161191271737. The reversal of 161191271720 is 27172191161.

It can be written as a sum of positive squares in 4 ways, for example, as 77833188196 + 83358083524 = 278986^2 + 288718^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 692630 + ... + 895610.

Almost surely, 2^161191271720 is an apocalyptic number.

161191271720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161191271720 is an abundant number, since it is smaller than the sum of its proper divisors (201509144800).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161191271720 is a wasteful number, since it uses less digits than its factorization.

161191271720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222845 (or 222841 counting only the distinct ones).

The product of its (nonzero) digits is 10584, while the sum is 38.

The spelling of 161191271720 in words is "one hundred sixty-one billion, one hundred ninety-one million, two hundred seventy-one thousand, seven hundred twenty".