161138431 has 4 divisors (see below), whose sum is σ = 161208000. Its totient is φ = 161068864.

The previous prime is 161138399. The next prime is 161138477. The reversal of 161138431 is 134831161.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 161138431 - 2⁵ = 161138399 is a prime.

It is a super-2 number, since 2×161138431² = 51931187890283522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161138431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161132431) 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, 31186 + ... + 35983.

It is an arithmetic number, because the mean of its divisors is an integer number (40302000).

Almost surely, 2^161138431 is an apocalyptic number.

161138431 is a deficient number, since it is larger than the sum of its proper divisors (69569).

161138431 is an equidigital number, since it uses as much as digits as its factorization.

161138431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69568.

The product of its digits is 1728, while the sum is 28.

The square root of 161138431 is about 12694.0313139680. The cubic root of 161138431 is about 544.1680553716.

Adding to 161138431 its reverse (134831161), we get a palindrome (295969592).

The spelling of 161138431 in words is "one hundred sixty-one million, one hundred thirty-eight thousand, four hundred thirty-one".