1221671808 has 384 divisors, whose sum is σ = 4324669440. Its totient is φ = 335923200.

The previous prime is 1221671791. The next prime is 1221671821. The reversal of 1221671808 is 8081761221.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6749478 + ... + 6749658.

It is an arithmetic number, because the mean of its divisors is an integer number (11262160).

Almost surely, 2^1221671808 is an apocalyptic number.

1221671808 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221671808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2162334720).

1221671808 is an abundant number, since it is smaller than the sum of its proper divisors (3102997632).

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

1221671808 is an equidigital number, since it uses as much as digits as its factorization.

1221671808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248 (or 224 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The square root of 1221671808 is about 34952.4220619974. The cubic root of 1221671808 is about 1069.0175883986.

The spelling of 1221671808 in words is "one billion, two hundred twenty-one million, six hundred seventy-one thousand, eight hundred eight".