4200021 has 24 divisors (see below), whose sum is σ = 6992960. Its totient is φ = 2379456.

The previous prime is 4200019. The next prime is 4200023. The reversal of 4200021 is 1200024.

It is an interprime number because it is at equal distance from previous prime (4200019) and next prime (4200023).

It is not a de Polignac number, because 4200021 - 2¹ = 4200019 is a prime.

It is a super-3 number, since 3×4200021³ (a number of 21 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is an Ulam number.

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 = 4199976 and 4200012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4200023) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10065 + ... + 10473.

Almost surely, 2^4200021 is an apocalyptic number.

It is an amenable number.

4200021 is a deficient number, since it is larger than the sum of its proper divisors (2792939).

4200021 is a wasteful number, since it uses less digits than its factorization.

4200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 585 (or 582 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 4200021 is about 2049.3952766609. The cubic root of 4200021 is about 161.3431335068.

Adding to 4200021 its reverse (1200024), we get a palindrome (5400045).

The spelling of 4200021 in words is "four million, two hundred thousand, twenty-one".