161330921995321 has 9 divisors (see below), whose sum is σ = 174695792558031. Its totient is φ = 148920698653272.

The previous prime is 161330921995261. The next prime is 161330921995349. The reversal of 161330921995321 is 123599129033161.

The square root of 161330921995321 is 12701611.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 23865521005225 + 137465400990096 = 4885235^2 + 11724564^2 .

It is not a de Polignac number, because 161330921995321 - 2⁷ = 161330921995193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161330921995361) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 164632420 + ... + 165609466.

It is an arithmetic number, because the mean of its divisors is an integer number (19410643617559).

Almost surely, 2^{161330921995321} is an apocalyptic number.

161330921995321 is the 12701611-st square number.

161330921995321 is the 6350806-th centered octagonal number.

It is an amenable number.

161330921995321 is a deficient number, since it is larger than the sum of its proper divisors (13364870562710).

161330921995321 is an frugal number, since it uses more digits than its factorization.

161330921995321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1954120 (or 977060 counting only the distinct ones).

The product of its (nonzero) digits is 2361960, while the sum is 55.

The spelling of 161330921995321 in words is "one hundred sixty-one trillion, three hundred thirty billion, nine hundred twenty-one million, nine hundred ninety-five thousand, three hundred twenty-one".