1221518880 has 120 divisors (see below), whose sum is σ = 4310989452. Its totient is φ = 325734912.

The previous prime is 1221518869. The next prime is 1221518887. The reversal of 1221518880 is 888151221.

It can be written as a sum of positive squares in 2 ways, for example, as 1104099984 + 117418896 = 33228^2 + 10836^2 .

It is a tau number, because it is divible by the number of its divisors (120).

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

It is not an unprimeable number, because it can be changed into a prime (1221518887) 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 19 ways as a sum of consecutive naturals, for example, 34167 + ... + 60086.

Almost surely, 2^1221518880 is an apocalyptic number.

1221518880 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221518880 is an abundant number, since it is smaller than the sum of its proper divisors (3089470572).

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

1221518880 is an equidigital number, since it uses as much as digits as its factorization.

1221518880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94280 (or 94263 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 36.

The square root of 1221518880 is about 34950.2343339784. The cubic root of 1221518880 is about 1068.9729802524.

The spelling of 1221518880 in words is "one billion, two hundred twenty-one million, five hundred eighteen thousand, eight hundred eighty".