161565401 has 2 divisors, whose sum is σ = 161565402. Its totient is φ = 161565400.

The previous prime is 161565389. The next prime is 161565407. The reversal of 161565401 is 104565161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 161315401 + 250000 = 12701^2 + 500^2 .

It is a cyclic number.

It is not a de Polignac number, because 161565401 - 2⁶ = 161565337 is a prime.

It is a super-2 number, since 2×161565401² = 52206757600581602, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161565407) 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, 80782700 + 80782701.

It is an arithmetic number, because the mean of its divisors is an integer number (80782701).

Almost surely, 2^161565401 is an apocalyptic number.

It is an amenable number.

161565401 is a deficient number, since it is larger than the sum of its proper divisors (1).

161565401 is an equidigital number, since it uses as much as digits as its factorization.

161565401 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 29.

The square root of 161565401 is about 12710.8379346131. The cubic root of 161565401 is about 544.6482605395.

The spelling of 161565401 in words is "one hundred sixty-one million, five hundred sixty-five thousand, four hundred one".