77997817 has 2 divisors, whose sum is σ = 77997818. Its totient is φ = 77997816.

The previous prime is 77997809. The next prime is 77997841. The reversal of 77997817 is 71879977.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 41165056 + 36832761 = 6416^2 + 6069^2 .

It is a cyclic number.

It is not a de Polignac number, because 77997817 - 2³ = 77997809 is a prime.

It is not a weakly prime, because it can be changed into another prime (77997877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38998908 + 38998909.

It is an arithmetic number, because the mean of its divisors is an integer number (38998909).

Almost surely, 2^77997817 is an apocalyptic number.

It is an amenable number.

77997817 is a deficient number, since it is larger than the sum of its proper divisors (1).

77997817 is an equidigital number, since it uses as much as digits as its factorization.

77997817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1555848, while the sum is 55.

The square root of 77997817 is about 8831.6372774248. The cubic root of 77997817 is about 427.2618821438.

It can be divided in two parts, 779 and 97817, that added together give a square (98596 = 314²).

The spelling of 77997817 in words is "seventy-seven million, nine hundred ninety-seven thousand, eight hundred seventeen".