81391363 has 2 divisors, whose sum is σ = 81391364. Its totient is φ = 81391362.

The previous prime is 81391361. The next prime is 81391397. The reversal of 81391363 is 36319318.

It is an a-pointer prime, because the next prime (81391397) can be obtained adding 81391363 to its sum of digits (34).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81391363 - 2¹ = 81391361 is a prime.

Together with 81391361, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81391361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40695681 + 40695682.

It is an arithmetic number, because the mean of its divisors is an integer number (40695682).

Almost surely, 2^81391363 is an apocalyptic number.

81391363 is a deficient number, since it is larger than the sum of its proper divisors (1).

81391363 is an equidigital number, since it uses as much as digits as its factorization.

81391363 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 34.

The square root of 81391363 is about 9021.7161892846. The cubic root of 81391363 is about 433.3705951522.

The spelling of 81391363 in words is "eighty-one million, three hundred ninety-one thousand, three hundred sixty-three".