77844989 has 4 divisors (see below), whose sum is σ = 82424124. Its totient is φ = 73265856.

The previous prime is 77844971. The next prime is 77845037. The reversal of 77844989 is 98944877.

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 42680089 + 35164900 = 6533^2 + 5930^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77844989 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77844959) 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, 2289542 + ... + 2289575.

It is an arithmetic number, because the mean of its divisors is an integer number (20606031).

Almost surely, 2^77844989 is an apocalyptic number.

It is an amenable number.

77844989 is a deficient number, since it is larger than the sum of its proper divisors (4579135).

77844989 is a wasteful number, since it uses less digits than its factorization.

77844989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4579134.

The product of its digits is 4064256, while the sum is 56.

The square root of 77844989 is about 8822.9807321562. The cubic root of 77844989 is about 426.9826423920.

The spelling of 77844989 in words is "seventy-seven million, eight hundred forty-four thousand, nine hundred eighty-nine".