1211221100 has 36 divisors (see below), whose sum is σ = 2782962504. Its totient is φ = 455988480.

The previous prime is 1211221097. The next prime is 1211221111. The reversal of 1211221100 is 11221121.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 354542 + ... + 357941.

It is an arithmetic number, because the mean of its divisors is an integer number (77304514).

Almost surely, 2^1211221100 is an apocalyptic number.

1211221100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1211221100 is an abundant number, since it is smaller than the sum of its proper divisors (1571741404).

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

1211221100 is a wasteful number, since it uses less digits than its factorization.

1211221100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 712514 (or 712507 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 11.

The square root of 1211221100 is about 34802.6019142247. The cubic root of 1211221100 is about 1065.9605754504.

Adding to 1211221100 its reverse (11221121), we get a palindrome (1222442221).

It can be divided in two parts, 121 and 1221100, that added together give a palindrome (1221221).

The spelling of 1211221100 in words is "one billion, two hundred eleven million, two hundred twenty-one thousand, one hundred".