81300031 has 4 divisors (see below), whose sum is σ = 85579000. Its totient is φ = 77021064.

The previous prime is 81300029. The next prime is 81300049. The reversal of 81300031 is 13000318.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13000318 = 2 ⋅6500159.

It is a cyclic number.

It is not a de Polignac number, because 81300031 - 2¹ = 81300029 is a prime.

It is a super-2 number, since 2×81300031² = 13219390081201922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81299978 and 81300014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81300071) 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, 2139456 + ... + 2139493.

It is an arithmetic number, because the mean of its divisors is an integer number (21394750).

Almost surely, 2^81300031 is an apocalyptic number.

81300031 is a deficient number, since it is larger than the sum of its proper divisors (4278969).

81300031 is a wasteful number, since it uses less digits than its factorization.

81300031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4278968.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 81300031 is about 9016.6529821215. The cubic root of 81300031 is about 433.2084345498.

Adding to 81300031 its reverse (13000318), we get a palindrome (94300349).

The spelling of 81300031 in words is "eighty-one million, three hundred thousand, thirty-one".