81312503 has 2 divisors, whose sum is σ = 81312504. Its totient is φ = 81312502.

The previous prime is 81312493. The next prime is 81312551. The reversal of 81312503 is 30521318.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81312503 - 2⁸ = 81312247 is a prime.

It is a super-2 number, since 2×81312503² = 13223446288250018, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81312703) 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, 40656251 + 40656252.

It is an arithmetic number, because the mean of its divisors is an integer number (40656252).

Almost surely, 2^81312503 is an apocalyptic number.

81312503 is a deficient number, since it is larger than the sum of its proper divisors (1).

81312503 is an equidigital number, since it uses as much as digits as its factorization.

81312503 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 81312503 is about 9017.3445647818. The cubic root of 81312503 is about 433.2305858302.

The spelling of 81312503 in words is "eighty-one million, three hundred twelve thousand, five hundred three".