81428539 has 4 divisors (see below), whose sum is σ = 82459360. Its totient is φ = 80397720.

The previous prime is 81428531. The next prime is 81428569. The reversal of 81428539 is 93582418.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81428539 - 2³ = 81428531 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81428531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 515292 + ... + 515449.

It is an arithmetic number, because the mean of its divisors is an integer number (20614840).

Almost surely, 2^81428539 is an apocalyptic number.

81428539 is a deficient number, since it is larger than the sum of its proper divisors (1030821).

81428539 is a wasteful number, since it uses less digits than its factorization.

81428539 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1030820.

The product of its digits is 69120, while the sum is 40.

The square root of 81428539 is about 9023.7763159334. The cubic root of 81428539 is about 433.4365666604.

The spelling of 81428539 in words is "eighty-one million, four hundred twenty-eight thousand, five hundred thirty-nine".