81331806251 has 2 divisors, whose sum is σ = 81331806252. Its totient is φ = 81331806250.

The previous prime is 81331806223. The next prime is 81331806253. The reversal of 81331806251 is 15260813318.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81331806251 - 2²² = 81327611947 is a prime.

It is a super-3 number, since 3×81331806251³ (a number of 34 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

Together with 81331806253, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81331806253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40665903125 + 40665903126.

It is an arithmetic number, because the mean of its divisors is an integer number (40665903126).

Almost surely, 2^81331806251 is an apocalyptic number.

81331806251 is a deficient number, since it is larger than the sum of its proper divisors (1).

81331806251 is an equidigital number, since it uses as much as digits as its factorization.

81331806251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34560, while the sum is 38.

The spelling of 81331806251 in words is "eighty-one billion, three hundred thirty-one million, eight hundred six thousand, two hundred fifty-one".