78785399081 has 2 divisors, whose sum is σ = 78785399082. Its totient is φ = 78785399080.

The previous prime is 78785399053. The next prime is 78785399123. The reversal of 78785399081 is 18099358787.

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., 78352967056 + 432432025 = 279916^2 + 20795^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78785399081 is a prime.

It is a super-2 number, since 2×78785399081² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 78785398999 and 78785399017.

It is not a weakly prime, because it can be changed into another prime (78785399041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39392699540 + 39392699541.

It is an arithmetic number, because the mean of its divisors is an integer number (39392699541).

Almost surely, 2^78785399081 is an apocalyptic number.

It is an amenable number.

78785399081 is a deficient number, since it is larger than the sum of its proper divisors (1).

78785399081 is an equidigital number, since it uses as much as digits as its factorization.

78785399081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30481920, while the sum is 65.

The spelling of 78785399081 in words is "seventy-eight billion, seven hundred eighty-five million, three hundred ninety-nine thousand, eighty-one".