81351696637 has 2 divisors, whose sum is σ = 81351696638. Its totient is φ = 81351696636.

The previous prime is 81351696581. The next prime is 81351696641. The reversal of 81351696637 is 73669615318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80284955716 + 1066740921 = 283346^2 + 32661^2 .

It is a cyclic number.

It is not a de Polignac number, because 81351696637 - 2¹⁹ = 81351172349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81351696667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40675848318 + 40675848319.

It is an arithmetic number, because the mean of its divisors is an integer number (40675848319).

Almost surely, 2^81351696637 is an apocalyptic number.

It is an amenable number.

81351696637 is a deficient number, since it is larger than the sum of its proper divisors (1).

81351696637 is an equidigital number, since it uses as much as digits as its factorization.

81351696637 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4898880, while the sum is 55.

The spelling of 81351696637 in words is "eighty-one billion, three hundred fifty-one million, six hundred ninety-six thousand, six hundred thirty-seven".