77831861 has 2 divisors, whose sum is σ = 77831862. Its totient is φ = 77831860.

The previous prime is 77831813. The next prime is 77831867. The reversal of 77831861 is 16813877.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 77545636 + 286225 = 8806^2 + 535^2 .

It is an emirp because it is prime and its reverse (16813877) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77831861 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77831867) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38915930 + 38915931.

It is an arithmetic number, because the mean of its divisors is an integer number (38915931).

Almost surely, 2^77831861 is an apocalyptic number.

It is an amenable number.

77831861 is a deficient number, since it is larger than the sum of its proper divisors (1).

77831861 is an equidigital number, since it uses as much as digits as its factorization.

77831861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 56448, while the sum is 41.

The square root of 77831861 is about 8822.2367345249. The cubic root of 77831861 is about 426.9586385208.

The spelling of 77831861 in words is "seventy-seven million, eight hundred thirty-one thousand, eight hundred sixty-one".