1221144500 has 24 divisors (see below), whose sum is σ = 2666980680. Its totient is φ = 488457600.

The previous prime is 1221144481. The next prime is 1221144503. The reversal of 1221144500 is 54411221.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 18164644 + 1202979856 = 4262^2 + 34684^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221144503) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1220645 + ... + 1221644.

It is an arithmetic number, because the mean of its divisors is an integer number (111124195).

Almost surely, 2^1221144500 is an apocalyptic number.

1221144500 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221144500 is an abundant number, since it is smaller than the sum of its proper divisors (1445836180).

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

1221144500 is a wasteful number, since it uses less digits than its factorization.

1221144500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2442308 (or 2442296 counting only the distinct ones).

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

The square root of 1221144500 is about 34944.8780223941. The cubic root of 1221144500 is about 1068.8637602195.

Adding to 1221144500 its reverse (54411221), we get a palindrome (1275555721).

The spelling of 1221144500 in words is "one billion, two hundred twenty-one million, one hundred forty-four thousand, five hundred".