81457219 has 2 divisors, whose sum is σ = 81457220. Its totient is φ = 81457218.

The previous prime is 81457213. The next prime is 81457247. The reversal of 81457219 is 91275418.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81457219 - 2¹⁹ = 80932931 is a prime.

It is a super-2 number, since 2×81457219² = 13270557054427922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81457213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40728609 + 40728610.

It is an arithmetic number, because the mean of its divisors is an integer number (40728610).

Almost surely, 2^81457219 is an apocalyptic number.

81457219 is a deficient number, since it is larger than the sum of its proper divisors (1).

81457219 is an equidigital number, since it uses as much as digits as its factorization.

81457219 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 37.

The square root of 81457219 is about 9025.3653111661. The cubic root of 81457219 is about 433.4874476813.

The spelling of 81457219 in words is "eighty-one million, four hundred fifty-seven thousand, two hundred nineteen".