81645339 has 8 divisors (see below), whose sum is σ = 115264080. Its totient is φ = 51228416.

The previous prime is 81645323. The next prime is 81645349. The reversal of 81645339 is 93354618.

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 81645339 - 2⁴ = 81645323 is a prime.

It is a super-2 number, since 2×81645339² = 13331922760849842, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81645297 and 81645306.

It is not an unprimeable number, because it can be changed into a prime (81645349) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 800394 + ... + 800495.

It is an arithmetic number, because the mean of its divisors is an integer number (14408010).

Almost surely, 2^81645339 is an apocalyptic number.

81645339 is a deficient number, since it is larger than the sum of its proper divisors (33618741).

81645339 is a wasteful number, since it uses less digits than its factorization.

81645339 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1600909.

The product of its digits is 77760, while the sum is 39.

The square root of 81645339 is about 9035.7810398438. The cubic root of 81645339 is about 433.8208945458.

The spelling of 81645339 in words is "eighty-one million, six hundred forty-five thousand, three hundred thirty-nine".