82135721 has 8 divisors (see below), whose sum is σ = 88016544. Its totient is φ = 76371520.

The previous prime is 82135717. The next prime is 82135723. The reversal of 82135721 is 12753128.

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

It is a cyclic number.

It is not a de Polignac number, because 82135721 - 2² = 82135717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (82135723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27695 + ... + 30516.

It is an arithmetic number, because the mean of its divisors is an integer number (11002068).

Almost surely, 2^82135721 is an apocalyptic number.

It is an amenable number.

82135721 is a deficient number, since it is larger than the sum of its proper divisors (5880823).

82135721 is a wasteful number, since it uses less digits than its factorization.

82135721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58311.

The product of its digits is 3360, while the sum is 29.

The square root of 82135721 is about 9062.8759784077. The cubic root of 82135721 is about 434.6877064471.

Adding to 82135721 its reverse (12753128), we get a palindrome (94888849).

The spelling of 82135721 in words is "eighty-two million, one hundred thirty-five thousand, seven hundred twenty-one".