71997977 has 2 divisors, whose sum is σ = 71997978. Its totient is φ = 71997976.

The previous prime is 71997971. The next prime is 71997979. The reversal of 71997977 is 77979917.

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., 60902416 + 11095561 = 7804^2 + 3331^2 .

It is an emirp because it is prime and its reverse (77979917) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71997977 - 2¹² = 71993881 is a prime.

Together with 71997979, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (71997971) 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, 35998988 + 35998989.

It is an arithmetic number, because the mean of its divisors is an integer number (35998989).

Almost surely, 2^71997977 is an apocalyptic number.

It is an amenable number.

71997977 is a deficient number, since it is larger than the sum of its proper divisors (1).

71997977 is an equidigital number, since it uses as much as digits as its factorization.

71997977 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1750329, while the sum is 56.

The square root of 71997977 is about 8485.1621669830. The cubic root of 71997977 is about 416.0128682687.

The spelling of 71997977 in words is "seventy-one million, nine hundred ninety-seven thousand, nine hundred seventy-seven".