1221526320 has 320 divisors, whose sum is σ = 4575135744. Its totient is φ = 263577600.

The previous prime is 1221526289. The next prime is 1221526331. The reversal of 1221526320 is 236251221.

It is a super-3 number, since 3×1221526320³ (a number of 28 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3902484 + ... + 3902796.

Almost surely, 2^1221526320 is an apocalyptic number.

1221526320 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221526320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2287567872).

1221526320 is an abundant number, since it is smaller than the sum of its proper divisors (3353609424).

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

1221526320 is a wasteful number, since it uses less digits than its factorization.

1221526320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 460 (or 454 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 1221526320 is about 34950.3407708709. The cubic root of 1221526320 is about 1068.9751505403.

Adding to 1221526320 its reverse (236251221), we get a palindrome (1457777541).

The spelling of 1221526320 in words is "one billion, two hundred twenty-one million, five hundred twenty-six thousand, three hundred twenty".