81143731 has 2 divisors, whose sum is σ = 81143732. Its totient is φ = 81143730.

The previous prime is 81143719. The next prime is 81143749. The reversal of 81143731 is 13734118.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81143731 - 2⁹ = 81143219 is a prime.

It is a super-2 number, since 2×81143731² = 13168610161200722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81143731.

It is not a weakly prime, because it can be changed into another prime (81143791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40571865 + 40571866.

It is an arithmetic number, because the mean of its divisors is an integer number (40571866).

Almost surely, 2^81143731 is an apocalyptic number.

81143731 is a deficient number, since it is larger than the sum of its proper divisors (1).

81143731 is an equidigital number, since it uses as much as digits as its factorization.

81143731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 28.

The square root of 81143731 is about 9007.9815164109. The cubic root of 81143731 is about 432.9306408220.

Adding to 81143731 its reverse (13734118), we get a palindrome (94877849).

The spelling of 81143731 in words is "eighty-one million, one hundred forty-three thousand, seven hundred thirty-one".