1221020200 has 24 divisors (see below), whose sum is σ = 2838872430. Its totient is φ = 488408000.

The previous prime is 1221020183. The next prime is 1221020231. The reversal of 1221020200 is 20201221.

It can be written as a sum of positive squares in 3 ways, for example, as 1015441956 + 205578244 = 31866^2 + 14338^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3052351 + ... + 3052750.

Almost surely, 2^1221020200 is an apocalyptic number.

1221020200 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221020200 is an abundant number, since it is smaller than the sum of its proper divisors (1617852230).

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

1221020200 is a wasteful number, since it uses less digits than its factorization.

1221020200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6105117 (or 6105108 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 1221020200 is about 34943.0994618394. The cubic root of 1221020200 is about 1068.8274925286.

Adding to 1221020200 its reverse (20201221), we get a palindrome (1241221421).

The spelling of 1221020200 in words is "one billion, two hundred twenty-one million, twenty thousand, two hundred".