81116251 has 2 divisors, whose sum is σ = 81116252. Its totient is φ = 81116250.

The previous prime is 81116249. The next prime is 81116257. The reversal of 81116251 is 15261118.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81116251 - 2¹ = 81116249 is a prime.

Together with 81116249, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81116257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40558125 + 40558126.

It is an arithmetic number, because the mean of its divisors is an integer number (40558126).

Almost surely, 2^81116251 is an apocalyptic number.

81116251 is a deficient number, since it is larger than the sum of its proper divisors (1).

81116251 is an equidigital number, since it uses as much as digits as its factorization.

81116251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 480, while the sum is 25.

The square root of 81116251 is about 9006.4560732843. The cubic root of 81116251 is about 432.8817634489.

Adding to 81116251 its reverse (15261118), we get a palindrome (96377369).

The spelling of 81116251 in words is "eighty-one million, one hundred sixteen thousand, two hundred fifty-one".