161561401 has 4 divisors (see below), whose sum is σ = 161672704. Its totient is φ = 161450100.

The previous prime is 161561381. The next prime is 161561417. The reversal of 161561401 is 104165161.

161561401 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 161561401 - 2⁵ = 161561369 is a prime.

It is a super-2 number, since 2×161561401² = 52204172586165602, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161561441) 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, 53445 + ... + 56386.

It is an arithmetic number, because the mean of its divisors is an integer number (40418176).

Almost surely, 2^161561401 is an apocalyptic number.

It is an amenable number.

161561401 is a deficient number, since it is larger than the sum of its proper divisors (111303).

161561401 is a wasteful number, since it uses less digits than its factorization.

161561401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111302.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 161561401 is about 12710.6805876003. The cubic root of 161561401 is about 544.6437657426.

The spelling of 161561401 in words is "one hundred sixty-one million, five hundred sixty-one thousand, four hundred one".