81335709 has 48 divisors (see below), whose sum is σ = 147743232. Its totient is φ = 41969664.

The previous prime is 81335707. The next prime is 81335717. The reversal of 81335709 is 90753318.

81335709 is a `hidden beast` number, since 81 + 3 + 3 + 570 + 9 = 666.

It is not a de Polignac number, because 81335709 - 2¹ = 81335707 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81335707) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 37437 + ... + 39549.

It is an arithmetic number, because the mean of its divisors is an integer number (3077984).

Almost surely, 2^81335709 is an apocalyptic number.

It is an amenable number.

81335709 is a deficient number, since it is larger than the sum of its proper divisors (66407523).

81335709 is a wasteful number, since it uses less digits than its factorization.

81335709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2186 (or 2183 counting only the distinct ones).

The product of its (nonzero) digits is 22680, while the sum is 36.

The square root of 81335709 is about 9018.6312154340. The cubic root of 81335709 is about 433.2717955349.

It can be divided in two parts, 81 and 335709, that added together give a triangular number (335790 = T₈₁₉).

The spelling of 81335709 in words is "eighty-one million, three hundred thirty-five thousand, seven hundred nine".