1211321100 has 144 divisors (see below), whose sum is σ = 3836004480. Its totient is φ = 292684800.

The previous prime is 1211321093. The next prime is 1211321123. The reversal of 1211321100 is 11231121.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1956591 + ... + 1957209.

It is an arithmetic number, because the mean of its divisors is an integer number (26638920).

Almost surely, 2^1211321100 is an apocalyptic number.

1211321100 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 1211321100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1918002240).

1211321100 is an abundant number, since it is smaller than the sum of its proper divisors (2624683380).

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

1211321100 is a wasteful number, since it uses less digits than its factorization.

1211321100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1240 (or 1233 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 12.

The square root of 1211321100 is about 34804.0385587650. The cubic root of 1211321100 is about 1065.9899103434.

Adding to 1211321100 its reverse (11231121), we get a palindrome (1222552221).

The spelling of 1211321100 in words is "one billion, two hundred eleven million, three hundred twenty-one thousand, one hundred".