81522579 has 4 divisors (see below), whose sum is σ = 108696776. Its totient is φ = 54348384.

The previous prime is 81522569. The next prime is 81522613. The reversal of 81522579 is 97522518.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 81522579 - 2⁸ = 81522323 is a prime.

It is a super-2 number, since 2×81522579² = 13291861773622482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81522569) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13587094 + ... + 13587099.

It is an arithmetic number, because the mean of its divisors is an integer number (27174194).

Almost surely, 2^81522579 is an apocalyptic number.

81522579 is a deficient number, since it is larger than the sum of its proper divisors (27174197).

81522579 is a wasteful number, since it uses less digits than its factorization.

81522579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27174196.

The product of its digits is 50400, while the sum is 39.

The square root of 81522579 is about 9028.9854911834. The cubic root of 81522579 is about 433.6033578707.

It can be divided in two parts, 8152 and 2579, that added together give a triangular number (10731 = T₁₄₆).

The spelling of 81522579 in words is "eighty-one million, five hundred twenty-two thousand, five hundred seventy-nine".