81439539 has 8 divisors (see below), whose sum is σ = 109806480. Its totient is φ = 53682816.

The previous prime is 81439507. The next prime is 81439541. The reversal of 81439539 is 93593418.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81439539 - 2⁵ = 81439507 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81439539.

It is not an unprimeable number, because it can be changed into a prime (81439559) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 152242 + ... + 152775.

It is an arithmetic number, because the mean of its divisors is an integer number (13725810).

Almost surely, 2^81439539 is an apocalyptic number.

81439539 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

81439539 is a deficient number, since it is larger than the sum of its proper divisors (28366941).

81439539 is a wasteful number, since it uses less digits than its factorization.

81439539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 305109.

The product of its digits is 116640, while the sum is 42.

The square root of 81439539 is about 9024.3857962744. The cubic root of 81439539 is about 433.4560831085.

The spelling of 81439539 in words is "eighty-one million, four hundred thirty-nine thousand, five hundred thirty-nine".