1221542120 has 16 divisors (see below), whose sum is σ = 2748469860. Its totient is φ = 488616832.

The previous prime is 1221542117. The next prime is 1221542131. The reversal of 1221542120 is 212451221.

It can be written as a sum of positive squares in 2 ways, for example, as 1200068164 + 21473956 = 34642^2 + 4634^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 1221542092 and 1221542101.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 15269237 + ... + 15269316.

Almost surely, 2^1221542120 is an apocalyptic number.

1221542120 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221542120 is an abundant number, since it is smaller than the sum of its proper divisors (1526927740).

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

1221542120 is a wasteful number, since it uses less digits than its factorization.

1221542120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30538564 (or 30538560 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 1221542120 is about 34950.5668051321. The cubic root of 1221542120 is about 1068.9797594557.

Adding to 1221542120 its reverse (212451221), we get a palindrome (1433993341).

The spelling of 1221542120 in words is "one billion, two hundred twenty-one million, five hundred forty-two thousand, one hundred twenty".