81821366 has 8 divisors (see below), whose sum is σ = 133889544. Its totient is φ = 37191520.

The previous prime is 81821359. The next prime is 81821371. The reversal of 81821366 is 66312818.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1859555 + ... + 1859598.

It is an arithmetic number, because the mean of its divisors is an integer number (16736193).

Almost surely, 2^81821366 is an apocalyptic number.

81821366 is a deficient number, since it is larger than the sum of its proper divisors (52068178).

81821366 is a wasteful number, since it uses less digits than its factorization.

81821366 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3719166.

The product of its digits is 13824, while the sum is 35.

The square root of 81821366 is about 9045.5163478930. The cubic root of 81821366 is about 434.1324427488.

The spelling of 81821366 in words is "eighty-one million, eight hundred twenty-one thousand, three hundred sixty-six".