161173921 has 2 divisors, whose sum is σ = 161173922. Its totient is φ = 161173920.

The previous prime is 161173913. The next prime is 161173937. The reversal of 161173921 is 129371161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 102819600 + 58354321 = 10140^2 + 7639^2 .

It is an emirp because it is prime and its reverse (129371161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161173921 - 2³ = 161173913 is a prime.

It is not a weakly prime, because it can be changed into another prime (161173321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80586960 + 80586961.

It is an arithmetic number, because the mean of its divisors is an integer number (80586961).

Almost surely, 2^161173921 is an apocalyptic number.

It is an amenable number.

161173921 is a deficient number, since it is larger than the sum of its proper divisors (1).

161173921 is an equidigital number, since it uses as much as digits as its factorization.

161173921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2268, while the sum is 31.

The square root of 161173921 is about 12695.4291380796. The cubic root of 161173921 is about 544.2080026114.

The spelling of 161173921 in words is "one hundred sixty-one million, one hundred seventy-three thousand, nine hundred twenty-one".