1211100120 has 64 divisors (see below), whose sum is σ = 4037004000. Its totient is φ = 322959744.

The previous prime is 1211100113. The next prime is 1211100127. The reversal of 1211100120 is 210011121.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1211100113) and next prime (1211100127).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211100127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 559615 + ... + 561774.

Almost surely, 2^1211100120 is an apocalyptic number.

1211100120 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1211100120 is an abundant number, since it is smaller than the sum of its proper divisors (2825903880).

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

1211100120 is a wasteful number, since it uses less digits than its factorization.

1211100120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1121409 (or 1121399 counting only the distinct ones).

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

The square root of 1211100120 is about 34800.8637823833. The cubic root of 1211100120 is about 1065.9250839385.

Adding to 1211100120 its reverse (210011121), we get a palindrome (1421111241).

The spelling of 1211100120 in words is "one billion, two hundred eleven million, one hundred thousand, one hundred twenty".