77847661 has 2 divisors, whose sum is σ = 77847662. Its totient is φ = 77847660.

The previous prime is 77847631. The next prime is 77847697. The reversal of 77847661 is 16674877.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77774761 + 72900 = 8819^2 + 270^2 .

It is an emirp because it is prime and its reverse (16674877) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77847661 - 2⁷ = 77847533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77847611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38923830 + 38923831.

It is an arithmetic number, because the mean of its divisors is an integer number (38923831).

Almost surely, 2^77847661 is an apocalyptic number.

It is an amenable number.

77847661 is a deficient number, since it is larger than the sum of its proper divisors (1).

77847661 is an equidigital number, since it uses as much as digits as its factorization.

77847661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 395136, while the sum is 46.

The square root of 77847661 is about 8823.1321536062. The cubic root of 77847661 is about 426.9875276757.

The spelling of 77847661 in words is "seventy-seven million, eight hundred forty-seven thousand, six hundred sixty-one".