1221646 has 4 divisors (see below), whose sum is σ = 1832472. Its totient is φ = 610822.

The previous prime is 1221641. The next prime is 1221653. The reversal of 1221646 is 6461221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6461221 = 13 ⋅497017.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 305410 + ... + 305413.

It is an arithmetic number, because the mean of its divisors is an integer number (458118).

2^1221646 is an apocalyptic number.

1221646 is a deficient number, since it is larger than the sum of its proper divisors (610826).

1221646 is an equidigital number, since it uses as much as digits as its factorization.

1221646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610825.

The product of its digits is 576, while the sum is 22.

The square root of 1221646 is about 1105.2809597564. The cubic root of 1221646 is about 106.9010060627.

Adding to 1221646 its reverse (6461221), we get a palindrome (7682867).

The spelling of 1221646 in words is "one million, two hundred twenty-one thousand, six hundred forty-six".