81396251 has 2 divisors, whose sum is σ = 81396252. Its totient is φ = 81396250.

The previous prime is 81396239. The next prime is 81396257. The reversal of 81396251 is 15269318.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81396251 is a prime.

It is a Chen prime.

It is equal to p_4746257 and since 81396251 and 4746257 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (81396257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40698125 + 40698126.

It is an arithmetic number, because the mean of its divisors is an integer number (40698126).

Almost surely, 2^81396251 is an apocalyptic number.

81396251 is a deficient number, since it is larger than the sum of its proper divisors (1).

81396251 is an equidigital number, since it uses as much as digits as its factorization.

81396251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 35.

The square root of 81396251 is about 9021.9870871111. The cubic root of 81396251 is about 433.3792704095.

The spelling of 81396251 in words is "eighty-one million, three hundred ninety-six thousand, two hundred fifty-one".