2001220421 has 2 divisors, whose sum is σ = 2001220422. Its totient is φ = 2001220420.

The previous prime is 2001220393. The next prime is 2001220451. The reversal of 2001220421 is 1240221002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2001220225 + 196 = 44735^2 + 14^2 .

It is a cyclic number.

It is not a de Polignac number, because 2001220421 - 2¹⁸ = 2000958277 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2001220396 and 2001220405.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2001220451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1000610210 + 1000610211.

It is an arithmetic number, because the mean of its divisors is an integer number (1000610211).

Almost surely, 2^2001220421 is an apocalyptic number.

It is an amenable number.

2001220421 is a deficient number, since it is larger than the sum of its proper divisors (1).

2001220421 is an equidigital number, since it uses as much as digits as its factorization.

2001220421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 2001220421 is about 44735.0021906784. The cubic root of 2001220421 is about 1260.1772701371.

Adding to 2001220421 its reverse (1240221002), we get a palindrome (3241441423).

The spelling of 2001220421 in words is "two billion, one million, two hundred twenty thousand, four hundred twenty-one".