81645223 has 8 divisors (see below), whose sum is σ = 93755520. Its totient is φ = 70316280.

The previous prime is 81645211. The next prime is 81645229. The reversal of 81645223 is 32254618.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81645223 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81645229) 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, 195115 + ... + 195532.

It is an arithmetic number, because the mean of its divisors is an integer number (11719440).

Almost surely, 2^81645223 is an apocalyptic number.

81645223 is a deficient number, since it is larger than the sum of its proper divisors (12110297).

81645223 is a wasteful number, since it uses less digits than its factorization.

81645223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 390677.

The product of its digits is 11520, while the sum is 31.

The square root of 81645223 is about 9035.7746209166. The cubic root of 81645223 is about 433.8206890911.

The spelling of 81645223 in words is "eighty-one million, six hundred forty-five thousand, two hundred twenty-three".