420020021 has 8 divisors (see below), whose sum is σ = 435901080. Its totient is φ = 404232192.

The previous prime is 420020009. The next prime is 420020039. The reversal of 420020021 is 120020024.

It can be written as a sum of positive squares in 4 ways, for example, as 220900 + 419799121 = 470^2 + 20489^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-420020021 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 = 420019984 and 420020011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (420020621) 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, 14060 + ... + 32213.

It is an arithmetic number, because the mean of its divisors is an integer number (54487635).

Almost surely, 2^420020021 is an apocalyptic number.

It is an amenable number.

420020021 is a deficient number, since it is larger than the sum of its proper divisors (15881059).

420020021 is a wasteful number, since it uses less digits than its factorization.

420020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46615.

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 420020021 is about 20494.3899884822. The cubic root of 420020021 is about 748.8991381133.

Adding to 420020021 its reverse (120020024), we get a palindrome (540040045).

The spelling of 420020021 in words is "four hundred twenty million, twenty thousand, twenty-one".