81217522 has 4 divisors (see below), whose sum is σ = 121826286. Its totient is φ = 40608760.

The previous prime is 81217501. The next prime is 81217523. The reversal of 81217522 is 22571218.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 22571218 = 2 ⋅11285609.

It can be written as a sum of positive squares in only one way, i.e., 76195441 + 5022081 = 8729^2 + 2241^2 .

It is not an unprimeable number, because it can be changed into a prime (81217523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20304379 + ... + 20304382.

Almost surely, 2^81217522 is an apocalyptic number.

81217522 is a deficient number, since it is larger than the sum of its proper divisors (40608764).

81217522 is a wasteful number, since it uses less digits than its factorization.

81217522 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40608763.

The product of its digits is 2240, while the sum is 28.

The square root of 81217522 is about 9012.0764532931. The cubic root of 81217522 is about 433.0618347974.

The spelling of 81217522 in words is "eighty-one million, two hundred seventeen thousand, five hundred twenty-two".