1221100110 has 40 divisors (see below), whose sum is σ = 3283404696. Its totient is φ = 325626480.

The previous prime is 1221100063. The next prime is 1221100121. The reversal of 1221100110 is 110011221.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 1221100092 and 1221100101.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 752956 + ... + 754575.

Almost surely, 2^1221100110 is an apocalyptic number.

1221100110 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1221100110 is an abundant number, since it is smaller than the sum of its proper divisors (2062304586).

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

1221100110 is a wasteful number, since it uses less digits than its factorization.

1221100110 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1507550 (or 1507541 counting only the distinct ones).

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

The square root of 1221100110 is about 34944.2428734692. The cubic root of 1221100110 is about 1068.8508085889.

Adding to 1221100110 its reverse (110011221), we get a palindrome (1331111331).

Subtracting from 1221100110 its reverse (110011221), we obtain a square (1111088889 = 33333²).

The spelling of 1221100110 in words is "one billion, two hundred twenty-one million, one hundred thousand, one hundred ten".