71881991 has 2 divisors, whose sum is σ = 71881992. Its totient is φ = 71881990.

The previous prime is 71881919. The next prime is 71882017. The reversal of 71881991 is 19918817.

Together with previous prime (71881919) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 71881991 - 2¹⁰ = 71880967 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71881291) 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 as a sum of consecutive naturals, namely, 35940995 + 35940996.

It is an arithmetic number, because the mean of its divisors is an integer number (35940996).

Almost surely, 2^71881991 is an apocalyptic number.

71881991 is a deficient number, since it is larger than the sum of its proper divisors (1).

71881991 is an equidigital number, since it uses as much as digits as its factorization.

71881991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 44.

The square root of 71881991 is about 8478.3247755674. The cubic root of 71881991 is about 415.7893545706.

The spelling of 71881991 in words is "seventy-one million, eight hundred eighty-one thousand, nine hundred ninety-one".