78394374781 has 2 divisors, whose sum is σ = 78394374782. Its totient is φ = 78394374780.

The previous prime is 78394374767. The next prime is 78394374853. The reversal of 78394374781 is 18747349387.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75996705625 + 2397669156 = 275675^2 + 48966^2 .

It is a cyclic number.

It is not a de Polignac number, because 78394374781 - 2¹¹ = 78394372733 is a prime.

It is a super-2 number, since 2×78394374781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78394374181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39197187390 + 39197187391.

It is an arithmetic number, because the mean of its divisors is an integer number (39197187391).

Almost surely, 2^78394374781 is an apocalyptic number.

It is an amenable number.

78394374781 is a deficient number, since it is larger than the sum of its proper divisors (1).

78394374781 is an equidigital number, since it uses as much as digits as its factorization.

78394374781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28449792, while the sum is 61.

The spelling of 78394374781 in words is "seventy-eight billion, three hundred ninety-four million, three hundred seventy-four thousand, seven hundred eighty-one".