77644681 has 2 divisors, whose sum is σ = 77644682. Its totient is φ = 77644680.

The previous prime is 77644667. The next prime is 77644703. The reversal of 77644681 is 18644677.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 56115081 + 21529600 = 7491^2 + 4640^2 .

It is an emirp because it is prime and its reverse (18644677) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77644681 - 2¹¹ = 77642633 is a prime.

It is a super-2 number, since 2×77644681² = 12057392975183522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (77644631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38822340 + 38822341.

It is an arithmetic number, because the mean of its divisors is an integer number (38822341).

Almost surely, 2^77644681 is an apocalyptic number.

It is an amenable number.

77644681 is a deficient number, since it is larger than the sum of its proper divisors (1).

77644681 is an equidigital number, since it uses as much as digits as its factorization.

77644681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 225792, while the sum is 43.

The square root of 77644681 is about 8811.6219278859. The cubic root of 77644681 is about 426.6160955552.

The spelling of 77644681 in words is "seventy-seven million, six hundred forty-four thousand, six hundred eighty-one".