161901601 has 4 divisors (see below), whose sum is σ = 162068292. Its totient is φ = 161734912.

The previous prime is 161901583. The next prime is 161901617. The reversal of 161901601 is 106109161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 106109161 = 3163 ⋅33547.

It can be written as a sum of positive squares in 2 ways, for example, as 158382225 + 3519376 = 12585^2 + 1876^2 .

It is a cyclic number.

It is not a de Polignac number, because 161901601 - 2⁷ = 161901473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161901671) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81880 + ... + 83833.

It is an arithmetic number, because the mean of its divisors is an integer number (40517073).

Almost surely, 2^161901601 is an apocalyptic number.

It is an amenable number.

161901601 is a deficient number, since it is larger than the sum of its proper divisors (166691).

161901601 is an equidigital number, since it uses as much as digits as its factorization.

161901601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166690.

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 161901601 is about 12724.0559964188. The cubic root of 161901601 is about 545.0257833662.

The spelling of 161901601 in words is "one hundred sixty-one million, nine hundred one thousand, six hundred one".