1221312021 has 8 divisors (see below), whose sum is σ = 1672427424. Its totient is φ = 792202320.

The previous prime is 1221312013. The next prime is 1221312031. The reversal of 1221312021 is 1202131221.

1221312021 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 1221312021 - 2³ = 1221312013 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221312031) 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, 5501295 + ... + 5501516.

It is an arithmetic number, because the mean of its divisors is an integer number (209053428).

Almost surely, 2^1221312021 is an apocalyptic number.

It is an amenable number.

1221312021 is a deficient number, since it is larger than the sum of its proper divisors (451115403).

1221312021 is a wasteful number, since it uses less digits than its factorization.

1221312021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11002851.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 1221312021 is about 34947.2748722987. The cubic root of 1221312021 is about 1068.9126348445.

Adding to 1221312021 its reverse (1202131221), we get a palindrome (2423443242).

The spelling of 1221312021 in words is "one billion, two hundred twenty-one million, three hundred twelve thousand, twenty-one".