81557363 has 2 divisors, whose sum is σ = 81557364. Its totient is φ = 81557362.

The previous prime is 81557339. The next prime is 81557393. The reversal of 81557363 is 36375518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81557363 - 2⁶ = 81557299 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (81557393) 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, 40778681 + 40778682.

It is an arithmetic number, because the mean of its divisors is an integer number (40778682).

Almost surely, 2^81557363 is an apocalyptic number.

81557363 is a deficient number, since it is larger than the sum of its proper divisors (1).

81557363 is an equidigital number, since it uses as much as digits as its factorization.

81557363 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 75600, while the sum is 38.

The square root of 81557363 is about 9030.9115265293. The cubic root of 81557363 is about 433.6650189662.

The spelling of 81557363 in words is "eighty-one million, five hundred fifty-seven thousand, three hundred sixty-three".