81213057347 has 2 divisors, whose sum is σ = 81213057348. Its totient is φ = 81213057346.

The previous prime is 81213057307. The next prime is 81213057391. The reversal of 81213057347 is 74375031218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81213057347 - 2⁸ = 81213057091 is a prime.

It is a super-2 number, since 2×81213057347² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81213057307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40606528673 + 40606528674.

It is an arithmetic number, because the mean of its divisors is an integer number (40606528674).

Almost surely, 2^81213057347 is an apocalyptic number.

81213057347 is a deficient number, since it is larger than the sum of its proper divisors (1).

81213057347 is an equidigital number, since it uses as much as digits as its factorization.

81213057347 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 141120, while the sum is 41.

The spelling of 81213057347 in words is "eighty-one billion, two hundred thirteen million, fifty-seven thousand, three hundred forty-seven".