1221636 has 48 divisors (see below), whose sum is σ = 3161088. Its totient is φ = 364800.

The previous prime is 1221631. The next prime is 1221641. The reversal of 1221636 is 6361221.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1221631) and next prime (1221641).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (1221631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6301 + ... + 6491.

It is an arithmetic number, because the mean of its divisors is an integer number (65856).

2^1221636 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1580544).

1221636 is an abundant number, since it is smaller than the sum of its proper divisors (1939452).

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

1221636 is a wasteful number, since it uses less digits than its factorization.

1221636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252 (or 250 counting only the distinct ones).

The product of its digits is 432, while the sum is 21.

The square root of 1221636 is about 1105.2764360105. The cubic root of 1221636 is about 106.9007143762.

Adding to 1221636 its reverse (6361221), we get a palindrome (7582857).

The spelling of 1221636 in words is "one million, two hundred twenty-one thousand, six hundred thirty-six".