81240563 has 2 divisors, whose sum is σ = 81240564. Its totient is φ = 81240562.

The previous prime is 81240547. The next prime is 81240613. The reversal of 81240563 is 36504218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81240563 - 2⁴ = 81240547 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (81240763) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40620281 + 40620282.

It is an arithmetic number, because the mean of its divisors is an integer number (40620282).

Almost surely, 2^81240563 is an apocalyptic number.

81240563 is a deficient number, since it is larger than the sum of its proper divisors (1).

81240563 is an equidigital number, since it uses as much as digits as its factorization.

81240563 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 81240563 is about 9013.3547028839. The cubic root of 81240563 is about 433.1027834090.

The spelling of 81240563 in words is "eighty-one million, two hundred forty thousand, five hundred sixty-three".