1211213100 has 72 divisors (see below), whose sum is σ = 3535554960. Its totient is φ = 320122880.

The previous prime is 1211213071. The next prime is 1211213111. The reversal of 1211213100 is 13121121.

It is a super-2 number, since 2×1211213100² = 2934074347223220000, which contains 22 as substring.

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 23 ways as a sum of consecutive naturals, for example, 16036 + ... + 51764.

It is an arithmetic number, because the mean of its divisors is an integer number (49104930).

Almost surely, 2^1211213100 is an apocalyptic number.

1211213100 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 1211213100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1767777480).

1211213100 is an abundant number, since it is smaller than the sum of its proper divisors (2324341860).

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

1211213100 is a wasteful number, since it uses less digits than its factorization.

1211213100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35859 (or 35852 counting only the distinct ones).

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

The square root of 1211213100 is about 34802.4869800996. The cubic root of 1211213100 is about 1065.9582285892.

Adding to 1211213100 its reverse (13121121), we get a palindrome (1224334221).

The spelling of 1211213100 in words is "one billion, two hundred eleven million, two hundred thirteen thousand, one hundred".