1221806385 has 24 divisors (see below), whose sum is σ = 2123357184. Its totient is φ = 649919520.

The previous prime is 1221806363. The next prime is 1221806423. The reversal of 1221806385 is 5836081221.

It is a happy number.

1221806385 is a `hidden beast` number, since 1 + 2 + 2 + 18 + 0 + 638 + 5 = 666.

It is not a de Polignac number, because 1221806385 - 2¹² = 1221802289 is a prime.

It is a Curzon number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 18211 + ... + 52680.

It is an arithmetic number, because the mean of its divisors is an integer number (88473216).

Almost surely, 2^1221806385 is an apocalyptic number.

1221806385 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1221806385 is a deficient number, since it is larger than the sum of its proper divisors (901550799).

1221806385 is a wasteful number, since it uses less digits than its factorization.

1221806385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71285 (or 71282 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 1221806385 is about 34954.3471545386. The cubic root of 1221806385 is about 1069.0568405929.

The spelling of 1221806385 in words is "one billion, two hundred twenty-one million, eight hundred six thousand, three hundred eighty-five".