1221390 has 48 divisors (see below), whose sum is σ = 3262896. Its totient is φ = 316800.

The previous prime is 1221383. The next prime is 1221391. The reversal of 1221390 is 931221.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221391) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3525 + ... + 3855.

It is an arithmetic number, because the mean of its divisors is an integer number (67977).

2^1221390 is an apocalyptic number.

1221390 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221390, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1631448).

1221390 is an abundant number, since it is smaller than the sum of its proper divisors (2041506).

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

1221390 is a wasteful number, since it uses less digits than its factorization.

1221390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 385 (or 382 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 1221390 is about 1105.1651460302. The cubic root of 1221390 is about 106.8935383867.

The spelling of 1221390 in words is "one million, two hundred twenty-one thousand, three hundred ninety".