78077861 has 2 divisors, whose sum is σ = 78077862. Its totient is φ = 78077860.

The previous prime is 78077837. The next prime is 78077863. The reversal of 78077861 is 16877087.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76562500 + 1515361 = 8750^2 + 1231^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78077861 is a prime.

Together with 78077863, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78077863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39038930 + 39038931.

It is an arithmetic number, because the mean of its divisors is an integer number (39038931).

Almost surely, 2^78077861 is an apocalyptic number.

It is an amenable number.

78077861 is a deficient number, since it is larger than the sum of its proper divisors (1).

78077861 is an equidigital number, since it uses as much as digits as its factorization.

78077861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 131712, while the sum is 44.

The square root of 78077861 is about 8836.1677779454. The cubic root of 78077861 is about 427.4079890439.

The spelling of 78077861 in words is "seventy-eight million, seventy-seven thousand, eight hundred sixty-one".