71891591 has 4 divisors (see below), whose sum is σ = 72293400. Its totient is φ = 71489784.

The previous prime is 71891587. The next prime is 71891683. The reversal of 71891591 is 19519817.

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 71891591 - 2² = 71891587 is a prime.

It is a super-2 number, since 2×71891591² = 10336801713022562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71891531) 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, 200636 + ... + 200993.

It is an arithmetic number, because the mean of its divisors is an integer number (18073350).

Almost surely, 2^71891591 is an apocalyptic number.

71891591 is a deficient number, since it is larger than the sum of its proper divisors (401809).

71891591 is a wasteful number, since it uses less digits than its factorization.

71891591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401808.

The product of its digits is 22680, while the sum is 41.

The square root of 71891591 is about 8478.8909062448. The cubic root of 71891591 is about 415.8078636115.

The spelling of 71891591 in words is "seventy-one million, eight hundred ninety-one thousand, five hundred ninety-one".