81864253 has 2 divisors, whose sum is σ = 81864254. Its totient is φ = 81864252.

The previous prime is 81864229. The next prime is 81864283. The reversal of 81864253 is 35246818.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52736644 + 29127609 = 7262^2 + 5397^2 .

It is a cyclic number.

It is not a de Polignac number, because 81864253 - 2⁵ = 81864221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81864283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40932126 + 40932127.

It is an arithmetic number, because the mean of its divisors is an integer number (40932127).

Almost surely, 2^81864253 is an apocalyptic number.

It is an amenable number.

81864253 is a deficient number, since it is larger than the sum of its proper divisors (1).

81864253 is an equidigital number, since it uses as much as digits as its factorization.

81864253 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46080, while the sum is 37.

The square root of 81864253 is about 9047.8866593255. The cubic root of 81864253 is about 434.2082802589.

The spelling of 81864253 in words is "eighty-one million, eight hundred sixty-four thousand, two hundred fifty-three".