161225809 has 2 divisors, whose sum is σ = 161225810. Its totient is φ = 161225808.

The previous prime is 161225789. The next prime is 161225833. The reversal of 161225809 is 908522161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 148157584 + 13068225 = 12172^2 + 3615^2 .

It is a cyclic number.

It is not a de Polignac number, because 161225809 - 2⁵ = 161225777 is a prime.

It is a super-2 number, since 2×161225809² = 51987522975408962, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161225879) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80612904 + 80612905.

It is an arithmetic number, because the mean of its divisors is an integer number (80612905).

Almost surely, 2^161225809 is an apocalyptic number.

It is an amenable number.

161225809 is a deficient number, since it is larger than the sum of its proper divisors (1).

161225809 is an equidigital number, since it uses as much as digits as its factorization.

161225809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 161225809 is about 12697.4725437782. The cubic root of 161225809 is about 544.2663967463.

The spelling of 161225809 in words is "one hundred sixty-one million, two hundred twenty-five thousand, eight hundred nine".