1221321504 has 144 divisors (see below), whose sum is σ = 3523455936. Its totient is φ = 368225280.

The previous prime is 1221321499. The next prime is 1221321509. The reversal of 1221321504 is 4051231221.

It is an interprime number because it is at equal distance from previous prime (1221321499) and next prime (1221321509).

It is a super-2 number, since 2×1221321504² = 2983252432265644032, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221321509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4643677 + ... + 4643939.

It is an arithmetic number, because the mean of its divisors is an integer number (24468444).

Almost surely, 2^1221321504 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 1221321504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1761727968).

1221321504 is an abundant number, since it is smaller than the sum of its proper divisors (2302134432).

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

1221321504 is a wasteful number, since it uses less digits than its factorization.

1221321504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 411 (or 342 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 1221321504 is about 34947.4105478503. The cubic root of 1221321504 is about 1068.9154013972.

Adding to 1221321504 its reverse (4051231221), we get a palindrome (5272552725).

The spelling of 1221321504 in words is "one billion, two hundred twenty-one million, three hundred twenty-one thousand, five hundred four".