1221122221 has 8 divisors (see below), whose sum is σ = 1336161888. Its totient is φ = 1106754000.

The previous prime is 1221122207. The next prime is 1221122239. The reversal of 1221122221 is 1222211221.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1221122221 - 2¹⁹ = 1220597933 is a prime.

It is a super-2 number, since 2×1221122221² = 2982278957239945682, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221122195 and 1221122204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221122281) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 164050 + ... + 171331.

It is an arithmetic number, because the mean of its divisors is an integer number (167020236).

Almost surely, 2^1221122221 is an apocalyptic number.

1221122221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221122221 is a deficient number, since it is larger than the sum of its proper divisors (115039667).

1221122221 is a wasteful number, since it uses less digits than its factorization.

1221122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335723.

The product of its digits is 64, while the sum is 16.

The square root of 1221122221 is about 34944.5592474708. The cubic root of 1221122221 is about 1068.8572599348.

Adding to 1221122221 its reverse (1222211221), we get a palindrome (2443333442).

The spelling of 1221122221 in words is "one billion, two hundred twenty-one million, one hundred twenty-two thousand, two hundred twenty-one".