1221090 has 64 divisors (see below), whose sum is σ = 3290112. Its totient is φ = 288000.

The previous prime is 1221089. The next prime is 1221097. The reversal of 1221090 is 901221.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is not an unprimeable number, because it can be changed into a prime (1221097) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12040 + ... + 12140.

It is an arithmetic number, because the mean of its divisors is an integer number (51408).

2^1221090 is an apocalyptic number.

1221090 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 1221090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1645056).

1221090 is an abundant number, since it is smaller than the sum of its proper divisors (2069022).

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

1221090 is a wasteful number, since it uses less digits than its factorization.

1221090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155.

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 1221090 is about 1105.0294113733. The cubic root of 1221090 is about 106.8847858759.

1221090 divided by its sum of digits (15) gives a triangular number (81406 = T₄₀₃).

The spelling of 1221090 in words is "one million, two hundred twenty-one thousand, ninety".