81374776787 has 2 divisors, whose sum is σ = 81374776788. Its totient is φ = 81374776786.

The previous prime is 81374776781. The next prime is 81374776837. The reversal of 81374776787 is 78767747318.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81374776787 - 2⁴ = 81374776771 is a prime.

It is not a weakly prime, because it can be changed into another prime (81374776781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40687388393 + 40687388394.

It is an arithmetic number, because the mean of its divisors is an integer number (40687388394).

Almost surely, 2^81374776787 is an apocalyptic number.

81374776787 is a deficient number, since it is larger than the sum of its proper divisors (1).

81374776787 is an equidigital number, since it uses as much as digits as its factorization.

81374776787 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77446656, while the sum is 65.

The spelling of 81374776787 in words is "eighty-one billion, three hundred seventy-four million, seven hundred seventy-six thousand, seven hundred eighty-seven".