1221231100 has 18 divisors (see below), whose sum is σ = 2650071704. Its totient is φ = 488492400.

The previous prime is 1221231083. The next prime is 1221231101. The reversal of 1221231100 is 11321221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221231101) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6106056 + ... + 6106255.

Almost surely, 2^1221231100 is an apocalyptic number.

1221231100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221231100 is an abundant number, since it is smaller than the sum of its proper divisors (1428840604).

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

1221231100 is a wasteful number, since it uses less digits than its factorization.

1221231100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12212325 (or 12212318 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 1221231100 is about 34946.1170947503. The cubic root of 1221231100 is about 1068.8890265205.

Adding to 1221231100 its reverse (11321221), we get a palindrome (1232552321).

The spelling of 1221231100 in words is "one billion, two hundred twenty-one million, two hundred thirty-one thousand, one hundred".