81305293 has 4 divisors (see below), whose sum is σ = 81385948. Its totient is φ = 81224640.

The previous prime is 81305269. The next prime is 81305297. The reversal of 81305293 is 39250318.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 39250318 = 2 ⋅19625159.

It can be written as a sum of positive squares in 2 ways, for example, as 37982569 + 43322724 = 6163^2 + 6582^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81305293 is a prime.

It is a super-2 number, since 2×81305293² = 13221101339631698, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81305297) 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, 38796 + ... + 40837.

It is an arithmetic number, because the mean of its divisors is an integer number (20346487).

Almost surely, 2^81305293 is an apocalyptic number.

It is an amenable number.

81305293 is a deficient number, since it is larger than the sum of its proper divisors (80655).

81305293 is a wasteful number, since it uses less digits than its factorization.

81305293 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80654.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 81305293 is about 9016.9447708190. The cubic root of 81305293 is about 433.2177805635.

The spelling of 81305293 in words is "eighty-one million, three hundred five thousand, two hundred ninety-three".