81503573 has 4 divisors (see below), whose sum is σ = 81523500. Its totient is φ = 81483648.

The previous prime is 81503537. The next prime is 81503579. The reversal of 81503573 is 37530518.

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

It can be written as a sum of positive squares in 2 ways, for example, as 43335889 + 38167684 = 6583^2 + 6178^2 .

It is a cyclic number.

It is not a de Polignac number, because 81503573 - 2⁶ = 81503509 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 (81503579) 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, 1340 + ... + 12837.

It is an arithmetic number, because the mean of its divisors is an integer number (20380875).

Almost surely, 2^81503573 is an apocalyptic number.

It is an amenable number.

81503573 is a deficient number, since it is larger than the sum of its proper divisors (19927).

81503573 is a wasteful number, since it uses less digits than its factorization.

81503573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19926.

The product of its (nonzero) digits is 12600, while the sum is 32.

The square root of 81503573 is about 9027.9329306326. The cubic root of 81503573 is about 433.5696587980.

The spelling of 81503573 in words is "eighty-one million, five hundred three thousand, five hundred seventy-three".