81403539 has 16 divisors (see below), whose sum is σ = 126147840. Its totient is φ = 45727200.

The previous prime is 81403513. The next prime is 81403547. The reversal of 81403539 is 93530418.

It is not a de Polignac number, because 81403539 - 2⁵ = 81403507 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81403549) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31612 + ... + 34089.

It is an arithmetic number, because the mean of its divisors is an integer number (7884240).

Almost surely, 2^81403539 is an apocalyptic number.

81403539 is a deficient number, since it is larger than the sum of its proper divisors (44744301).

81403539 is a wasteful number, since it uses less digits than its factorization.

81403539 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65770.

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 81403539 is about 9022.3909802225. The cubic root of 81403539 is about 433.3922045591.

The spelling of 81403539 in words is "eighty-one million, four hundred three thousand, five hundred thirty-nine".