161233921 has 2 divisors, whose sum is σ = 161233922. Its totient is φ = 161233920.

The previous prime is 161233909. The next prime is 161233927. The reversal of 161233921 is 129332161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 84916225 + 76317696 = 9215^2 + 8736^2 .

It is a cyclic number.

It is not a de Polignac number, because 161233921 - 2¹⁵ = 161201153 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 161233921.

It is not a weakly prime, because it can be changed into another prime (161233927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80616960 + 80616961.

It is an arithmetic number, because the mean of its divisors is an integer number (80616961).

Almost surely, 2^161233921 is an apocalyptic number.

It is an amenable number.

161233921 is a deficient number, since it is larger than the sum of its proper divisors (1).

161233921 is an equidigital number, since it uses as much as digits as its factorization.

161233921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1944, while the sum is 28.

The square root of 161233921 is about 12697.7919734102. The cubic root of 161233921 is about 544.2755247617.

The spelling of 161233921 in words is "one hundred sixty-one million, two hundred thirty-three thousand, nine hundred twenty-one".