81213263 has 2 divisors, whose sum is σ = 81213264. Its totient is φ = 81213262.

The previous prime is 81213229. The next prime is 81213287. The reversal of 81213263 is 36231218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81213263 - 2²⁶ = 14104399 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81213203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40606631 + 40606632.

It is an arithmetic number, because the mean of its divisors is an integer number (40606632).

Almost surely, 2^81213263 is an apocalyptic number.

81213263 is a deficient number, since it is larger than the sum of its proper divisors (1).

81213263 is an equidigital number, since it uses as much as digits as its factorization.

81213263 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 26.

The square root of 81213263 is about 9011.8401561501. The cubic root of 81213263 is about 433.0542648275.

The spelling of 81213263 in words is "eighty-one million, two hundred thirteen thousand, two hundred sixty-three".