81964725251 has 2 divisors, whose sum is σ = 81964725252. Its totient is φ = 81964725250.

The previous prime is 81964725239. The next prime is 81964725277. The reversal of 81964725251 is 15252746918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81964725251 - 2¹⁰ = 81964724227 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81964725251.

It is not a weakly prime, because it can be changed into another prime (81964725151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40982362625 + 40982362626.

It is an arithmetic number, because the mean of its divisors is an integer number (40982362626).

Almost surely, 2^81964725251 is an apocalyptic number.

81964725251 is a deficient number, since it is larger than the sum of its proper divisors (1).

81964725251 is an equidigital number, since it uses as much as digits as its factorization.

81964725251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1209600, while the sum is 50.

The spelling of 81964725251 in words is "eighty-one billion, nine hundred sixty-four million, seven hundred twenty-five thousand, two hundred fifty-one".