1221509 has 8 divisors (see below), whose sum is σ = 1283160. Its totient is φ = 1161216.

The previous prime is 1221503. The next prime is 1221523. The reversal of 1221509 is 9051221.

It can be written as a sum of positive squares in 4 ways, for example, as 616225 + 605284 = 785^2 + 778^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 1221509 - 2²⁰ = 172933 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221503) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1829 + ... + 2405.

It is an arithmetic number, because the mean of its divisors is an integer number (160395).

2^1221509 is an apocalyptic number.

It is an amenable number.

1221509 is a deficient number, since it is larger than the sum of its proper divisors (61651).

1221509 is an equidigital number, since it uses as much as digits as its factorization.

1221509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 679.

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 1221509 is about 1105.2189828265. The cubic root of 1221509 is about 106.8970098190.

The spelling of 1221509 in words is "one million, two hundred twenty-one thousand, five hundred nine".