161508491 has 4 divisors (see below), whose sum is σ = 161588184. Its totient is φ = 161428800.

The previous prime is 161508467. The next prime is 161508499. The reversal of 161508491 is 194805161.

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 161508491 - 2⁶ = 161508427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161508499) 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, 36725 + ... + 40886.

It is an arithmetic number, because the mean of its divisors is an integer number (40397046).

Almost surely, 2^161508491 is an apocalyptic number.

161508491 is a deficient number, since it is larger than the sum of its proper divisors (79693).

161508491 is an equidigital number, since it uses as much as digits as its factorization.

161508491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79692.

The product of its (nonzero) digits is 8640, while the sum is 35.

The square root of 161508491 is about 12708.5990966747. The cubic root of 161508491 is about 544.5843038335.

The spelling of 161508491 in words is "one hundred sixty-one million, five hundred eight thousand, four hundred ninety-one".