1221545200 has 90 divisors (see below), whose sum is σ = 3117845336. Its totient is φ = 459832320.

The previous prime is 1221545197. The next prime is 1221545209. The reversal of 1221545200 is 25451221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221545209) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 110317 + ... + 120883.

Almost surely, 2^1221545200 is an apocalyptic number.

1221545200 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 1221545200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1558922668).

1221545200 is an abundant number, since it is smaller than the sum of its proper divisors (1896300136).

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

1221545200 is a wasteful number, since it uses less digits than its factorization.

1221545200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10619 (or 10591 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 22.

The square root of 1221545200 is about 34950.6108673368. The cubic root of 1221545200 is about 1068.9806578979.

Adding to 1221545200 its reverse (25451221), we get a palindrome (1246996421).

The spelling of 1221545200 in words is "one billion, two hundred twenty-one million, five hundred forty-five thousand, two hundred".