163861591 has 4 divisors (see below), whose sum is σ = 170986032. Its totient is φ = 156737152.

The previous prime is 163861561. The next prime is 163861597. The reversal of 163861591 is 195168361.

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 163861591 - 2⁵ = 163861559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (163861597) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3562186 + ... + 3562231.

It is an arithmetic number, because the mean of its divisors is an integer number (42746508).

Almost surely, 2^163861591 is an apocalyptic number.

163861591 is a deficient number, since it is larger than the sum of its proper divisors (7124441).

163861591 is an equidigital number, since it uses as much as digits as its factorization.

163861591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7124440.

The product of its digits is 38880, while the sum is 40.

The square root of 163861591 is about 12800.8433706534. The cubic root of 163861591 is about 547.2163383981.

The spelling of 163861591 in words is "one hundred sixty-three million, eight hundred sixty-one thousand, five hundred ninety-one".