1221816960 has 960 divisors, whose sum is σ = 5613882120. Its totient is φ = 250822656.

The previous prime is 1221816949. The next prime is 1221816961. The reversal of 1221816960 is 696181221.

It can be written as a sum of positive squares in 4 ways, for example, as 1008189504 + 213627456 = 31752^2 + 14616^2 .

It is a tau number, because it is divible by the number of its divisors (960).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221816961) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 33022062 + ... + 33022098.

Almost surely, 2^1221816960 is an apocalyptic number.

1221816960 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 1221816960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2806941060).

1221816960 is an abundant number, since it is smaller than the sum of its proper divisors (4392065160).

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

1221816960 is a wasteful number, since it uses less digits than its factorization.

1221816960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95 (or 67 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 1221816960 is about 34954.4984229498. The cubic root of 1221816960 is about 1069.0599248905.

The spelling of 1221816960 in words is "one billion, two hundred twenty-one million, eight hundred sixteen thousand, nine hundred sixty".