81235073 has 4 divisors (see below), whose sum is σ = 81277140. Its totient is φ = 81193008.

The previous prime is 81235069. The next prime is 81235111. The reversal of 81235073 is 37053218.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 37053218 = 2 ⋅18526609.

It can be written as a sum of positive squares in 2 ways, for example, as 74511424 + 6723649 = 8632^2 + 2593^2 .

It is a cyclic number.

It is not a de Polignac number, because 81235073 - 2² = 81235069 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81235043) 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, 17990 + ... + 22047.

It is an arithmetic number, because the mean of its divisors is an integer number (20319285).

Almost surely, 2^81235073 is an apocalyptic number.

It is an amenable number.

81235073 is a deficient number, since it is larger than the sum of its proper divisors (42067).

81235073 is a wasteful number, since it uses less digits than its factorization.

81235073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42066.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 81235073 is about 9013.0501496441. The cubic root of 81235073 is about 433.0930272488.

The spelling of 81235073 in words is "eighty-one million, two hundred thirty-five thousand, seventy-three".