1221795808 has 48 divisors (see below), whose sum is σ = 2540837376. Its totient is φ = 577422720.

The previous prime is 1221795791. The next prime is 1221795821. The reversal of 1221795808 is 8085971221.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28335 + ... + 56977.

It is an arithmetic number, because the mean of its divisors is an integer number (52934112).

Almost surely, 2^1221795808 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221795808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1270418688).

1221795808 is an abundant number, since it is smaller than the sum of its proper divisors (1319041568).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221795808 is a wasteful number, since it uses less digits than its factorization.

1221795808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28727 (or 28719 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 43.

The square root of 1221795808 is about 34954.1958568639. The cubic root of 1221795808 is about 1069.0537556942.

The spelling of 1221795808 in words is "one billion, two hundred twenty-one million, seven hundred ninety-five thousand, eight hundred eight".