163991591 has 2 divisors, whose sum is σ = 163991592. Its totient is φ = 163991590.

The previous prime is 163991573. The next prime is 163991609. The reversal of 163991591 is 195199361.

It is a balanced prime because it is at equal distance from previous prime (163991573) and next prime (163991609).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-163991591 is a prime.

It is a super-2 number, since 2×163991591² = 53786483837422562, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (163991501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 81995795 + 81995796.

It is an arithmetic number, because the mean of its divisors is an integer number (81995796).

Almost surely, 2^163991591 is an apocalyptic number.

163991591 is a deficient number, since it is larger than the sum of its proper divisors (1).

163991591 is an equidigital number, since it uses as much as digits as its factorization.

163991591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 65610, while the sum is 44.

The square root of 163991591 is about 12805.9201543661. The cubic root of 163991591 is about 547.3610119593.

The spelling of 163991591 in words is "one hundred sixty-three million, nine hundred ninety-one thousand, five hundred ninety-one".