79840781 has 2 divisors, whose sum is σ = 79840782. Its totient is φ = 79840780.

The previous prime is 79840777. The next prime is 79840801. The reversal of 79840781 is 18704897.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52330756 + 27510025 = 7234^2 + 5245^2 .

It is a cyclic number.

It is not a de Polignac number, because 79840781 - 2² = 79840777 is a prime.

It is a super-2 number, since 2×79840781² = 12749100621379922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (79840181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39920390 + 39920391.

It is an arithmetic number, because the mean of its divisors is an integer number (39920391).

Almost surely, 2^79840781 is an apocalyptic number.

It is an amenable number.

79840781 is a deficient number, since it is larger than the sum of its proper divisors (1).

79840781 is an equidigital number, since it uses as much as digits as its factorization.

79840781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 112896, while the sum is 44.

The square root of 79840781 is about 8935.3668643207. The cubic root of 79840781 is about 430.6008923754.

The spelling of 79840781 in words is "seventy-nine million, eight hundred forty thousand, seven hundred eighty-one".