71667989 has 2 divisors, whose sum is σ = 71667990. Its totient is φ = 71667988.

The previous prime is 71667979. The next prime is 71667991. The reversal of 71667989 is 98976617.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61105489 + 10562500 = 7817^2 + 3250^2 .

It is an emirp because it is prime and its reverse (98976617) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71667989 - 2²⁰ = 70619413 is a prime.

It is a Sophie Germain prime.

Together with 71667991, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 71667989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71667929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35833994 + 35833995.

It is an arithmetic number, because the mean of its divisors is an integer number (35833995).

Almost surely, 2^71667989 is an apocalyptic number.

It is an amenable number.

71667989 is a deficient number, since it is larger than the sum of its proper divisors (1).

71667989 is an equidigital number, since it uses as much as digits as its factorization.

71667989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1143072, while the sum is 53.

The square root of 71667989 is about 8465.6948326762. The cubic root of 71667989 is about 415.3763248257.

The spelling of 71667989 in words is "seventy-one million, six hundred sixty-seven thousand, nine hundred eighty-nine".