71689991 has 2 divisors, whose sum is σ = 71689992. Its totient is φ = 71689990.

The previous prime is 71689951. The next prime is 71689997. The reversal of 71689991 is 19998617.

It is a strong prime.

It is an emirp because it is prime and its reverse (19998617) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71689991 - 2¹⁸ = 71427847 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71689997) 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, 35844995 + 35844996.

It is an arithmetic number, because the mean of its divisors is an integer number (35844996).

Almost surely, 2^71689991 is an apocalyptic number.

71689991 is a deficient number, since it is larger than the sum of its proper divisors (1).

71689991 is an equidigital number, since it uses as much as digits as its factorization.

71689991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 50.

The square root of 71689991 is about 8466.9942128243. The cubic root of 71689991 is about 415.4188271802.

The spelling of 71689991 in words is "seventy-one million, six hundred eighty-nine thousand, nine hundred ninety-one".