71857991 has 2 divisors, whose sum is σ = 71857992. Its totient is φ = 71857990.

The previous prime is 71857987. The next prime is 71857993. The reversal of 71857991 is 19975817.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 71857991 - 2² = 71857987 is a prime.

Together with 71857993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71857993) 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 as a sum of consecutive naturals, namely, 35928995 + 35928996.

It is an arithmetic number, because the mean of its divisors is an integer number (35928996).

Almost surely, 2^71857991 is an apocalyptic number.

71857991 is a deficient number, since it is larger than the sum of its proper divisors (1).

71857991 is an equidigital number, since it uses as much as digits as its factorization.

71857991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 158760, while the sum is 47.

The square root of 71857991 is about 8476.9092834594. The cubic root of 71857991 is about 415.7430747576.

The spelling of 71857991 in words is "seventy-one million, eight hundred fifty-seven thousand, nine hundred ninety-one".