81424513 has 2 divisors, whose sum is σ = 81424514. Its totient is φ = 81424512.

The previous prime is 81424463. The next prime is 81424517. The reversal of 81424513 is 31542418.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65480464 + 15944049 = 8092^2 + 3993^2 .

It is a cyclic number.

It is not a de Polignac number, because 81424513 - 2⁹ = 81424001 is a prime.

It is not a weakly prime, because it can be changed into another prime (81424517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40712256 + 40712257.

It is an arithmetic number, because the mean of its divisors is an integer number (40712257).

Almost surely, 2^81424513 is an apocalyptic number.

It is an amenable number.

81424513 is a deficient number, since it is larger than the sum of its proper divisors (1).

81424513 is an equidigital number, since it uses as much as digits as its factorization.

81424513 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3840, while the sum is 28.

The square root of 81424513 is about 9023.5532358379. The cubic root of 81424513 is about 433.4294232011.

The spelling of 81424513 in words is "eighty-one million, four hundred twenty-four thousand, five hundred thirteen".