81399608819 has 2 divisors, whose sum is σ = 81399608820. Its totient is φ = 81399608818.

The previous prime is 81399608747. The next prime is 81399608861. The reversal of 81399608819 is 91880699318.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81399608819 - 2¹² = 81399604723 is a prime.

It is a super-2 number, since 2×81399608819² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81399608869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40699804409 + 40699804410.

It is an arithmetic number, because the mean of its divisors is an integer number (40699804410).

Almost surely, 2^81399608819 is an apocalyptic number.

81399608819 is a deficient number, since it is larger than the sum of its proper divisors (1).

81399608819 is an equidigital number, since it uses as much as digits as its factorization.

81399608819 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6718464, while the sum is 62.

The spelling of 81399608819 in words is "eighty-one billion, three hundred ninety-nine million, six hundred eight thousand, eight hundred nineteen".