1221601326 has 64 divisors (see below), whose sum is σ = 2704181760. Its totient is φ = 364828160.

The previous prime is 1221601309. The next prime is 1221601327. The reversal of 1221601326 is 6231061221.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1221601296 and 1221601305.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221601327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1509610 + ... + 1510418.

It is an arithmetic number, because the mean of its divisors is an integer number (42252840).

Almost surely, 2^1221601326 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221601326, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1352090880).

1221601326 is an abundant number, since it is smaller than the sum of its proper divisors (1482580434).

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

1221601326 is a wasteful number, since it uses less digits than its factorization.

1221601326 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1129.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 1221601326 is about 34951.4137911473. The cubic root of 1221601326 is about 1068.9970297002.

Adding to 1221601326 its reverse (6231061221), we get a palindrome (7452662547).

The spelling of 1221601326 in words is "one billion, two hundred twenty-one million, six hundred one thousand, three hundred twenty-six".