81356663 has 2 divisors, whose sum is σ = 81356664. Its totient is φ = 81356662.

The previous prime is 81356621. The next prime is 81356677. The reversal of 81356663 is 36665318.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81356663 - 2¹⁴ = 81340279 is a prime.

It is a super-2 number, since 2×81356663² = 13237813228991138, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81356063) 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, 40678331 + 40678332.

It is an arithmetic number, because the mean of its divisors is an integer number (40678332).

Almost surely, 2^81356663 is an apocalyptic number.

81356663 is a deficient number, since it is larger than the sum of its proper divisors (1).

81356663 is an equidigital number, since it uses as much as digits as its factorization.

81356663 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 77760, while the sum is 38.

The square root of 81356663 is about 9019.7928468452. The cubic root of 81356663 is about 433.3089993568.

The spelling of 81356663 in words is "eighty-one million, three hundred fifty-six thousand, six hundred sixty-three".