81643459 has 2 divisors, whose sum is σ = 81643460. Its totient is φ = 81643458.

The previous prime is 81643427. The next prime is 81643481. The reversal of 81643459 is 95434618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81643459 - 2⁵ = 81643427 is a prime.

It is not a weakly prime, because it can be changed into another prime (81646459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40821729 + 40821730.

It is an arithmetic number, because the mean of its divisors is an integer number (40821730).

Almost surely, 2^81643459 is an apocalyptic number.

81643459 is a deficient number, since it is larger than the sum of its proper divisors (1).

81643459 is an equidigital number, since it uses as much as digits as its factorization.

81643459 is an evil number, because the sum of its binary digits is even.

The product of its digits is 103680, while the sum is 40.

The square root of 81643459 is about 9035.6770083929. The cubic root of 81643459 is about 433.8175647393.

The spelling of 81643459 in words is "eighty-one million, six hundred forty-three thousand, four hundred fifty-nine".