1211021100 has 216 divisors, whose sum is σ = 3998056608. Its totient is φ = 306201600.

The previous prime is 1211021087. The next prime is 1211021111. The reversal of 1211021100 is 11201121.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1364857 + ... + 1365743.

Almost surely, 2^1211021100 is an apocalyptic number.

1211021100 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 1211021100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1999028304).

1211021100 is an abundant number, since it is smaller than the sum of its proper divisors (2787035508).

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

1211021100 is a wasteful number, since it uses less digits than its factorization.

1211021100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 985 (or 975 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

The square root of 1211021100 is about 34799.7284472164. The cubic root of 1211021100 is about 1065.9019008202.

Adding to 1211021100 its reverse (11201121), we get a palindrome (1222222221).

It can be divided in two parts, 1211021 and 100, that added together give a palindrome (1211121).

The spelling of 1211021100 in words is "one billion, two hundred eleven million, twenty-one thousand, one hundred".