81573229 has 4 divisors (see below), whose sum is σ = 81602140. Its totient is φ = 81544320.

The previous prime is 81573199. The next prime is 81573253. The reversal of 81573229 is 92237518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 92237518 = 2 ⋅46118759.

It can be written as a sum of positive squares in 2 ways, for example, as 62884900 + 18688329 = 7930^2 + 4323^2 .

It is a cyclic number.

It is not a de Polignac number, because 81573229 - 2⁷ = 81573101 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81573299) 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, 9702 + ... + 16039.

It is an arithmetic number, because the mean of its divisors is an integer number (20400535).

Almost surely, 2^81573229 is an apocalyptic number.

It is an amenable number.

81573229 is a deficient number, since it is larger than the sum of its proper divisors (28911).

81573229 is a wasteful number, since it uses less digits than its factorization.

81573229 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28910.

The product of its digits is 30240, while the sum is 37.

The square root of 81573229 is about 9031.7899111970. The cubic root of 81573229 is about 433.6931385735.

The spelling of 81573229 in words is "eighty-one million, five hundred seventy-three thousand, two hundred twenty-nine".