1221661 has 8 divisors (see below), whose sum is σ = 1404800. Its totient is φ = 1040688.

The previous prime is 1221659. The next prime is 1221667. The reversal of 1221661 is 1661221.

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 1221661 - 2¹ = 1221659 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 (1221667) 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, 955 + ... + 1831.

It is an arithmetic number, because the mean of its divisors is an integer number (175600).

2^1221661 is an apocalyptic number.

It is an amenable number.

1221661 is a deficient number, since it is larger than the sum of its proper divisors (183139).

1221661 is an equidigital number, since it uses as much as digits as its factorization.

1221661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1083.

The product of its digits is 144, while the sum is 19.

The square root of 1221661 is about 1105.2877453406. The cubic root of 1221661 is about 106.9014435894.

Adding to 1221661 its reverse (1661221), we get a palindrome (2882882).

The spelling of 1221661 in words is "one million, two hundred twenty-one thousand, six hundred sixty-one".