1210221100 has 72 divisors (see below), whose sum is σ = 2887815168. Its totient is φ = 436564800.

The previous prime is 1210221043. The next prime is 1210221101. The reversal of 1210221100 is 11220121.

It is a super-2 number, since 2×1210221100² = 2929270221770420000, which contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (1210221101) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 135369 + ... + 144031.

It is an arithmetic number, because the mean of its divisors is an integer number (40108544).

Almost surely, 2^1210221100 is an apocalyptic number.

1210221100 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 1210221100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1443907584).

1210221100 is an abundant number, since it is smaller than the sum of its proper divisors (1677594068).

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

1210221100 is a wasteful number, since it uses less digits than its factorization.

1210221100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8815 (or 8808 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 1210221100 is about 34788.2322057330. The cubic root of 1210221100 is about 1065.6671376772.

Adding to 1210221100 its reverse (11220121), we get a palindrome (1221441221).

The spelling of 1210221100 in words is "one billion, two hundred ten million, two hundred twenty-one thousand, one hundred".