81767251 has 2 divisors, whose sum is σ = 81767252. Its totient is φ = 81767250.

The previous prime is 81767249. The next prime is 81767419. The reversal of 81767251 is 15276718.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81767251 - 2¹ = 81767249 is a prime.

Together with 81767249, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81767251.

It is not a weakly prime, because it can be changed into another prime (81767551) 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, 40883625 + 40883626.

It is an arithmetic number, because the mean of its divisors is an integer number (40883626).

Almost surely, 2^81767251 is an apocalyptic number.

81767251 is a deficient number, since it is larger than the sum of its proper divisors (1).

81767251 is an equidigital number, since it uses as much as digits as its factorization.

81767251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23520, while the sum is 37.

The square root of 81767251 is about 9042.5245921700. The cubic root of 81767251 is about 434.0367128294.

The spelling of 81767251 in words is "eighty-one million, seven hundred sixty-seven thousand, two hundred fifty-one".