1221611 has 4 divisors (see below), whose sum is σ = 1239912. Its totient is φ = 1203312.

The previous prime is 1221601. The next prime is 1221631. The reversal of 1221611 is 1161221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1161221 = 79 ⋅14699.

It is a cyclic number.

It is not a de Polignac number, because 1221611 - 2¹⁸ = 959467 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9050 + ... + 9183.

It is an arithmetic number, because the mean of its divisors is an integer number (309978).

2^1221611 is an apocalyptic number.

1221611 is a deficient number, since it is larger than the sum of its proper divisors (18301).

1221611 is an equidigital number, since it uses as much as digits as its factorization.

1221611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18300.

The product of its digits is 24, while the sum is 14.

The square root of 1221611 is about 1105.2651265647. The cubic root of 1221611 is about 106.8999851529.

Adding to 1221611 its reverse (1161221), we get a palindrome (2382832).

It can be divided in two parts, 1221 and 611, that multiplied together give a triangular number (746031 = T₁₂₂₁).

The spelling of 1221611 in words is "one million, two hundred twenty-one thousand, six hundred eleven".