71866391 has 2 divisors, whose sum is σ = 71866392. Its totient is φ = 71866390.

The previous prime is 71866369. The next prime is 71866393. The reversal of 71866391 is 19366817.

It is a strong prime.

It is an emirp because it is prime and its reverse (19366817) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71866391 is a prime.

It is a Sophie Germain prime.

Together with 71866393, 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 (71866393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35933195 + 35933196.

It is an arithmetic number, because the mean of its divisors is an integer number (35933196).

Almost surely, 2^71866391 is an apocalyptic number.

71866391 is a deficient number, since it is larger than the sum of its proper divisors (1).

71866391 is an equidigital number, since it uses as much as digits as its factorization.

71866391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 41.

The square root of 71866391 is about 8477.4047325818. The cubic root of 71866391 is about 415.7592738642.

The spelling of 71866391 in words is "seventy-one million, eight hundred sixty-six thousand, three hundred ninety-one".