81457217 has 8 divisors (see below), whose sum is σ = 86639616. Its totient is φ = 76318272.

The previous prime is 81457213. The next prime is 81457219. The reversal of 81457217 is 71275418.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81457217 - 2² = 81457213 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81457213) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6953 + ... + 14534.

It is an arithmetic number, because the mean of its divisors is an integer number (10829952).

Almost surely, 2^81457217 is an apocalyptic number.

It is an amenable number.

81457217 is a deficient number, since it is larger than the sum of its proper divisors (5182399).

81457217 is a wasteful number, since it uses less digits than its factorization.

81457217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21727.

The product of its digits is 15680, while the sum is 35.

The square root of 81457217 is about 9025.3652003672. The cubic root of 81457217 is about 433.4874441336.

The spelling of 81457217 in words is "eighty-one million, four hundred fifty-seven thousand, two hundred seventeen".