191639 has 6 divisors (see below), whose sum is σ = 222984. Its totient is φ = 164220.

The previous prime is 191627. The next prime is 191657. The reversal of 191639 is 936191.

It is a de Polignac number, because none of the positive numbers 2^k-191639 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 (191669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1907 + ... + 2004.

It is an arithmetic number, because the mean of its divisors is an integer number (37164).

2¹⁹¹⁶³⁹ is an apocalyptic number.

191639 is a deficient number, since it is larger than the sum of its proper divisors (31345).

191639 is an equidigital number, since it uses as much as digits as its factorization.

191639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3925 (or 3918 counting only the distinct ones).

The product of its digits is 1458, while the sum is 29.

The square root of 191639 is about 437.7659191851. The cubic root of 191639 is about 57.6538037326.

The spelling of 191639 in words is "one hundred ninety-one thousand, six hundred thirty-nine".