77973661 has 2 divisors, whose sum is σ = 77973662. Its totient is φ = 77973660.

The previous prime is 77973659. The next prime is 77973667. The reversal of 77973661 is 16637977.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77968900 + 4761 = 8830^2 + 69^2 .

It is a cyclic number.

It is not a de Polignac number, because 77973661 - 2¹ = 77973659 is a prime.

Together with 77973659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77973667) 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, 38986830 + 38986831.

It is an arithmetic number, because the mean of its divisors is an integer number (38986831).

Almost surely, 2^77973661 is an apocalyptic number.

It is an amenable number.

77973661 is a deficient number, since it is larger than the sum of its proper divisors (1).

77973661 is an equidigital number, since it uses as much as digits as its factorization.

77973661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 333396, while the sum is 46.

The square root of 77973661 is about 8830.2695881836. The cubic root of 77973661 is about 427.2177697824.

The spelling of 77973661 in words is "seventy-seven million, nine hundred seventy-three thousand, six hundred sixty-one".