81489643 has 2 divisors, whose sum is σ = 81489644. Its totient is φ = 81489642.

The previous prime is 81489637. The next prime is 81489647. The reversal of 81489643 is 34698418.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81489643 - 2¹³ = 81481451 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81489643.

It is not a weakly prime, because it can be changed into another prime (81489647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40744821 + 40744822.

It is an arithmetic number, because the mean of its divisors is an integer number (40744822).

Almost surely, 2^81489643 is an apocalyptic number.

81489643 is a deficient number, since it is larger than the sum of its proper divisors (1).

81489643 is an equidigital number, since it uses as much as digits as its factorization.

81489643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 165888, while the sum is 43.

The square root of 81489643 is about 9027.1614032319. The cubic root of 81489643 is about 433.5449565294.

The spelling of 81489643 in words is "eighty-one million, four hundred eighty-nine thousand, six hundred forty-three".