77865989 has 2 divisors, whose sum is σ = 77865990. Its totient is φ = 77865988.

The previous prime is 77865979. The next prime is 77866021. The reversal of 77865989 is 98956877.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 53904964 + 23961025 = 7342^2 + 4895^2 .

It is a cyclic number.

It is not a de Polignac number, because 77865989 - 2¹⁶ = 77800453 is a prime.

It is a super-2 number, since 2×77865989² = 12126224485896242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77865919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38932994 + 38932995.

It is an arithmetic number, because the mean of its divisors is an integer number (38932995).

Almost surely, 2^77865989 is an apocalyptic number.

It is an amenable number.

77865989 is a deficient number, since it is larger than the sum of its proper divisors (1).

77865989 is an equidigital number, since it uses as much as digits as its factorization.

77865989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7620480, while the sum is 59.

The square root of 77865989 is about 8824.1707259096. The cubic root of 77865989 is about 427.0210341987.

The spelling of 77865989 in words is "seventy-seven million, eight hundred sixty-five thousand, nine hundred eighty-nine".