77644991 has 2 divisors, whose sum is σ = 77644992. Its totient is φ = 77644990.

The previous prime is 77644937. The next prime is 77645011. The reversal of 77644991 is 19944677.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (19944677) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77644991 - 2⁶ = 77644927 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 (77644921) 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, 38822495 + 38822496.

It is an arithmetic number, because the mean of its divisors is an integer number (38822496).

Almost surely, 2^77644991 is an apocalyptic number.

77644991 is a deficient number, since it is larger than the sum of its proper divisors (1).

77644991 is an equidigital number, since it uses as much as digits as its factorization.

77644991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 381024, while the sum is 47.

The square root of 77644991 is about 8811.6395182735. The cubic root of 77644991 is about 426.6166633160.

The spelling of 77644991 in words is "seventy-seven million, six hundred forty-four thousand, nine hundred ninety-one".