1221918 has 8 divisors (see below), whose sum is σ = 2443848. Its totient is φ = 407304.

The previous prime is 1221917. The next prime is 1221937. The reversal of 1221918 is 8191221.

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

1221918 is an admirable number.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221917) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 101821 + ... + 101832.

It is an arithmetic number, because the mean of its divisors is an integer number (305481).

2^1221918 is an apocalyptic number.

1221918 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

1221918 is a wasteful number, since it uses less digits than its factorization.

1221918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203658.

The product of its digits is 288, while the sum is 24.

The square root of 1221918 is about 1105.4039985453. The cubic root of 1221918 is about 106.9089393254.

The spelling of 1221918 in words is "one million, two hundred twenty-one thousand, nine hundred eighteen".