1021212221 has 4 divisors (see below), whose sum is σ = 1025791872. Its totient is φ = 1016632572.

The previous prime is 1021212211. The next prime is 1021212233. The reversal of 1021212221 is 1222121201.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1021212221 - 2²² = 1017017917 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1021212196 and 1021212205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021212211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2289491 + ... + 2289936.

It is an arithmetic number, because the mean of its divisors is an integer number (256447968).

Almost surely, 2^1021212221 is an apocalyptic number.

It is an amenable number.

1021212221 is a deficient number, since it is larger than the sum of its proper divisors (4579651).

1021212221 is an equidigital number, since it uses as much as digits as its factorization.

1021212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4579650.

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 1021212221 is about 31956.4112659729. The cubic root of 1021212221 is about 1007.0213259340.

Adding to 1021212221 its reverse (1222121201), we get a palindrome (2243333422).

The spelling of 1021212221 in words is "one billion, twenty-one million, two hundred twelve thousand, two hundred twenty-one".