81512231 has 2 divisors, whose sum is σ = 81512232. Its totient is φ = 81512230.

The previous prime is 81512201. The next prime is 81512257. The reversal of 81512231 is 13221518.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81512231 is a prime.

It is a super-2 number, since 2×81512231² = 13288487605194722, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 81512197 and 81512206.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81512201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40756115 + 40756116.

It is an arithmetic number, because the mean of its divisors is an integer number (40756116).

Almost surely, 2^81512231 is an apocalyptic number.

81512231 is a deficient number, since it is larger than the sum of its proper divisors (1).

81512231 is an equidigital number, since it uses as much as digits as its factorization.

81512231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 480, while the sum is 23.

The square root of 81512231 is about 9028.4124296578. The cubic root of 81512231 is about 433.5850107352.

Adding to 81512231 its reverse (13221518), we get a palindrome (94733749).

The spelling of 81512231 in words is "eighty-one million, five hundred twelve thousand, two hundred thirty-one".