1221245553 has 16 divisors (see below), whose sum is σ = 1786180032. Its totient is φ = 736056000.

The previous prime is 1221245551. The next prime is 1221245561. The reversal of 1221245553 is 3555421221.

It is not a de Polignac number, because 1221245553 - 2¹ = 1221245551 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1221245553.

It is not an unprimeable number, because it can be changed into a prime (1221245551) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 96258 + ... + 108203.

It is an arithmetic number, because the mean of its divisors is an integer number (111636252).

Almost surely, 2^1221245553 is an apocalyptic number.

It is an amenable number.

1221245553 is a deficient number, since it is larger than the sum of its proper divisors (564934479).

1221245553 is a wasteful number, since it uses less digits than its factorization.

1221245553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204656.

The product of its digits is 12000, while the sum is 30.

The square root of 1221245553 is about 34946.3238839223. The cubic root of 1221245553 is about 1068.8932431923.

Adding to 1221245553 its reverse (3555421221), we get a palindrome (4776666774).

The spelling of 1221245553 in words is "one billion, two hundred twenty-one million, two hundred forty-five thousand, five hundred fifty-three".