81131217 has 8 divisors (see below), whose sum is σ = 108736224. Its totient is φ = 53806848.

The previous prime is 81131201. The next prime is 81131221. The reversal of 81131217 is 71213118.

It is a happy number.

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

It is not a de Polignac number, because 81131217 - 2⁴ = 81131201 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81131227) 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, 69483 + ... + 70640.

It is an arithmetic number, because the mean of its divisors is an integer number (13592028).

Almost surely, 2^81131217 is an apocalyptic number.

It is an amenable number.

81131217 is a deficient number, since it is larger than the sum of its proper divisors (27605007).

81131217 is a wasteful number, since it uses less digits than its factorization.

81131217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140319.

The product of its digits is 336, while the sum is 24.

The square root of 81131217 is about 9007.2868834072. The cubic root of 81131217 is about 432.9083841321.

The spelling of 81131217 in words is "eighty-one million, one hundred thirty-one thousand, two hundred seventeen".