81440459 has 2 divisors, whose sum is σ = 81440460. Its totient is φ = 81440458.

The previous prime is 81440449. The next prime is 81440461. The reversal of 81440459 is 95404418.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81440459 is a prime.

Together with 81440461, 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 (81440449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40720229 + 40720230.

It is an arithmetic number, because the mean of its divisors is an integer number (40720230).

Almost surely, 2^81440459 is an apocalyptic number.

81440459 is a deficient number, since it is larger than the sum of its proper divisors (1).

81440459 is an equidigital number, since it uses as much as digits as its factorization.

81440459 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23040, while the sum is 35.

The square root of 81440459 is about 9024.4367691286. The cubic root of 81440459 is about 433.4577153136.

The spelling of 81440459 in words is "eighty-one million, four hundred forty thousand, four hundred fifty-nine".