81358073 has 4 divisors (see below), whose sum is σ = 86143860. Its totient is φ = 76572288.

The previous prime is 81358001. The next prime is 81358087. The reversal of 81358073 is 37085318.

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 60637369 + 20720704 = 7787^2 + 4552^2 .

It is a cyclic number.

It is not a de Polignac number, because 81358073 - 2¹² = 81353977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81358873) 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, 2392868 + ... + 2392901.

It is an arithmetic number, because the mean of its divisors is an integer number (21535965).

Almost surely, 2^81358073 is an apocalyptic number.

It is an amenable number.

81358073 is a deficient number, since it is larger than the sum of its proper divisors (4785787).

81358073 is a wasteful number, since it uses less digits than its factorization.

81358073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4785786.

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 81358073 is about 9019.8710079468. The cubic root of 81358073 is about 433.3115025820.

The spelling of 81358073 in words is "eighty-one million, three hundred fifty-eight thousand, seventy-three".