77820461 has 2 divisors, whose sum is σ = 77820462. Its totient is φ = 77820460.

The previous prime is 77820439. The next prime is 77820487. The reversal of 77820461 is 16402877.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 68790436 + 9030025 = 8294^2 + 3005^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77820461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77820761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38910230 + 38910231.

It is an arithmetic number, because the mean of its divisors is an integer number (38910231).

Almost surely, 2^77820461 is an apocalyptic number.

It is an amenable number.

77820461 is a deficient number, since it is larger than the sum of its proper divisors (1).

77820461 is an equidigital number, since it uses as much as digits as its factorization.

77820461 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18816, while the sum is 35.

The square root of 77820461 is about 8821.5906162098. The cubic root of 77820461 is about 426.9377920188.

The spelling of 77820461 in words is "seventy-seven million, eight hundred twenty thousand, four hundred sixty-one".