81291957337 has 2 divisors, whose sum is σ = 81291957338. Its totient is φ = 81291957336.

The previous prime is 81291957323. The next prime is 81291957403. The reversal of 81291957337 is 73375919218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52336170441 + 28955786896 = 228771^2 + 170164^2 .

It is a cyclic number.

It is not a de Polignac number, because 81291957337 - 2³⁵ = 46932218969 is a prime.

It is not a weakly prime, because it can be changed into another prime (81291957317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40645978668 + 40645978669.

It is an arithmetic number, because the mean of its divisors is an integer number (40645978669).

Almost surely, 2^81291957337 is an apocalyptic number.

It is an amenable number.

81291957337 is a deficient number, since it is larger than the sum of its proper divisors (1).

81291957337 is an equidigital number, since it uses as much as digits as its factorization.

81291957337 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2857680, while the sum is 55.

The spelling of 81291957337 in words is "eighty-one billion, two hundred ninety-one million, nine hundred fifty-seven thousand, three hundred thirty-seven".