1221441636 has 48 divisors (see below), whose sum is σ = 3026963520. Its totient is φ = 382018560.

The previous prime is 1221441623. The next prime is 1221441667. The reversal of 1221441636 is 6361441221.

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 58480 + ... + 76568.

It is an arithmetic number, because the mean of its divisors is an integer number (63061740).

Almost surely, 2^1221441636 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 1221441636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1513481760).

1221441636 is an abundant number, since it is smaller than the sum of its proper divisors (1805521884).

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

1221441636 is a wasteful number, since it uses less digits than its factorization.

1221441636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18444 (or 18442 counting only the distinct ones).

The product of its digits is 6912, while the sum is 30.

The square root of 1221441636 is about 34949.1292595395. The cubic root of 1221441636 is about 1068.9504472430.

Adding to 1221441636 its reverse (6361441221), we get a palindrome (7582882857).

The spelling of 1221441636 in words is "one billion, two hundred twenty-one million, four hundred forty-one thousand, six hundred thirty-six".