1211220100 has 36 divisors (see below), whose sum is σ = 2661635200. Its totient is φ = 478352160.

The previous prime is 1211220091. The next prime is 1211220107. The reversal of 1211220100 is 10221121.

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 (1211220107) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 68760 + ... + 84559.

Almost surely, 2^1211220100 is an apocalyptic number.

1211220100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1211220100 is an abundant number, since it is smaller than the sum of its proper divisors (1450415100).

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

1211220100 is a wasteful number, since it uses less digits than its factorization.

1211220100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153412 (or 153405 counting only the distinct ones).

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

The square root of 1211220100 is about 34802.5875474799. The cubic root of 1211220100 is about 1065.9602820933.

Adding to 1211220100 its reverse (10221121), we get a palindrome (1221441221).

It can be divided in two parts, 121 and 1220100, that added together give a palindrome (1220221).

The spelling of 1211220100 in words is "one billion, two hundred eleven million, two hundred twenty thousand, one hundred".