81281503 has 2 divisors, whose sum is σ = 81281504. Its totient is φ = 81281502.

The previous prime is 81281491. The next prime is 81281507. The reversal of 81281503 is 30518218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81281503 - 2¹⁷ = 81150431 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81281507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40640751 + 40640752.

It is an arithmetic number, because the mean of its divisors is an integer number (40640752).

Almost surely, 2^81281503 is an apocalyptic number.

81281503 is a deficient number, since it is larger than the sum of its proper divisors (1).

81281503 is an equidigital number, since it uses as much as digits as its factorization.

81281503 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 81281503 is about 9015.6254913345. The cubic root of 81281503 is about 433.1755231409.

The spelling of 81281503 in words is "eighty-one million, two hundred eighty-one thousand, five hundred three".