81543013 has 2 divisors, whose sum is σ = 81543014. Its totient is φ = 81543012.

The previous prime is 81542977. The next prime is 81543023. The reversal of 81543013 is 31034518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80586529 + 956484 = 8977^2 + 978^2 .

It is a cyclic number.

It is not a de Polignac number, because 81543013 - 2²⁵ = 47988581 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81543023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40771506 + 40771507.

It is an arithmetic number, because the mean of its divisors is an integer number (40771507).

Almost surely, 2^81543013 is an apocalyptic number.

It is an amenable number.

81543013 is a deficient number, since it is larger than the sum of its proper divisors (1).

81543013 is an equidigital number, since it uses as much as digits as its factorization.

81543013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 81543013 is about 9030.1169981346. The cubic root of 81543013 is about 433.6395830529.

The spelling of 81543013 in words is "eighty-one million, five hundred forty-three thousand, thirteen".