1221864 has 48 divisors (see below), whose sum is σ = 3556800. Its totient is φ = 348768.

The previous prime is 1221863. The next prime is 1221907. The reversal of 1221864 is 4681221.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (1221863) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 657 + ... + 1695.

It is an arithmetic number, because the mean of its divisors is an integer number (74100).

2^1221864 is an apocalyptic number.

1221864 is a gapful number since it is divisible by the number (14) 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 1221864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1778400).

1221864 is an abundant number, since it is smaller than the sum of its proper divisors (2334936).

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

1221864 is a wasteful number, since it uses less digits than its factorization.

1221864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1062 (or 1051 counting only the distinct ones).

The product of its digits is 768, while the sum is 24.

The square root of 1221864 is about 1105.3795728165. The cubic root of 1221864 is about 106.9073644331.

The spelling of 1221864 in words is "one million, two hundred twenty-one thousand, eight hundred sixty-four".