1213213221 has 24 divisors (see below), whose sum is σ = 1982539104. Its totient is φ = 735279120.

The previous prime is 1213213217. The next prime is 1213213237. The reversal of 1213213221 is 1223123121.

1213213221 is a `hidden beast` number, since 1 + 21 + 321 + 322 + 1 = 666.

It is not a de Polignac number, because 1213213221 - 2² = 1213213217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1213213194 and 1213213203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1213213121) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 224266 + ... + 229611.

It is an arithmetic number, because the mean of its divisors is an integer number (82605796).

Almost surely, 2^1213213221 is an apocalyptic number.

1213213221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1213213221 is a deficient number, since it is larger than the sum of its proper divisors (769325883).

1213213221 is an equidigital number, since it uses as much as digits as its factorization.

1213213221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 453903 (or 453891 counting only the distinct ones).

The product of its digits is 144, while the sum is 18.

The square root of 1213213221 is about 34831.2104440830. The cubic root of 1213213221 is about 1066.5446579958.

Adding to 1213213221 its reverse (1223123121), we get a palindrome (2436336342).

The spelling of 1213213221 in words is "one billion, two hundred thirteen million, two hundred thirteen thousand, two hundred twenty-one".