81038731 has 4 divisors (see below), whose sum is σ = 83833200. Its totient is φ = 78244264.

The previous prime is 81038723. The next prime is 81038767. The reversal of 81038731 is 13783018.

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

It is a cyclic number.

It is not a de Polignac number, because 81038731 - 2³ = 81038723 is a prime.

It is a super-2 number, since 2×81038731² = 13134551844180722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81038693 and 81038702.

It is not an unprimeable number, because it can be changed into a prime (81038701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1397191 + ... + 1397248.

It is an arithmetic number, because the mean of its divisors is an integer number (20958300).

Almost surely, 2^81038731 is an apocalyptic number.

81038731 is a deficient number, since it is larger than the sum of its proper divisors (2794469).

81038731 is a wasteful number, since it uses less digits than its factorization.

81038731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2794468.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 81038731 is about 9002.1514650666. The cubic root of 81038731 is about 432.7438227801.

The spelling of 81038731 in words is "eighty-one million, thirty-eight thousand, seven hundred thirty-one".