77644661 has 4 divisors (see below), whose sum is σ = 82212012. Its totient is φ = 73077312.

The previous prime is 77644639. The next prime is 77644667. The reversal of 77644661 is 16644677.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 59197636 + 18447025 = 7694^2 + 4295^2 .

It is a cyclic number.

It is not a de Polignac number, because 77644661 - 2²² = 73450357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77644667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2283650 + ... + 2283683.

It is an arithmetic number, because the mean of its divisors is an integer number (20553003).

Almost surely, 2^77644661 is an apocalyptic number.

It is an amenable number.

77644661 is a deficient number, since it is larger than the sum of its proper divisors (4567351).

77644661 is a wasteful number, since it uses less digits than its factorization.

77644661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4567350.

The product of its digits is 169344, while the sum is 41.

The square root of 77644661 is about 8811.6207930210. The cubic root of 77644661 is about 426.6160589254.

The spelling of 77644661 in words is "seventy-seven million, six hundred forty-four thousand, six hundred sixty-one".