81573713 has 4 divisors (see below), whose sum is σ = 87848628. Its totient is φ = 75298800.

The previous prime is 81573703. The next prime is 81573719. The reversal of 81573713 is 31737518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31737518 = 2 ⋅15868759.

It can be written as a sum of positive squares in 2 ways, for example, as 4695889 + 76877824 = 2167^2 + 8768^2 .

It is a cyclic number.

It is not a de Polignac number, because 81573713 - 2⁶ = 81573649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81573719) 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, 3137438 + ... + 3137463.

It is an arithmetic number, because the mean of its divisors is an integer number (21962157).

Almost surely, 2^81573713 is an apocalyptic number.

It is an amenable number.

81573713 is a deficient number, since it is larger than the sum of its proper divisors (6274915).

81573713 is a wasteful number, since it uses less digits than its factorization.

81573713 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6274914.

The product of its digits is 17640, while the sum is 35.

The square root of 81573713 is about 9031.8167054032. The cubic root of 81573713 is about 433.6939963184.

The spelling of 81573713 in words is "eighty-one million, five hundred seventy-three thousand, seven hundred thirteen".