30021 has 4 divisors (see below), whose sum is σ = 40032. Its totient is φ = 20012.

The previous prime is 30013. The next prime is 30029. The reversal of 30021 is 12003.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12003 = 3 ⋅4001.

It is an interprime number because it is at equal distance from previous prime (30013) and next prime (30029).

It is a cyclic number.

It is not a de Polignac number, because 30021 - 2³ = 30013 is a prime.

It is an Ulam number.

It is a D-number.

30021 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 29991 and 30009.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (30029) 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, 5001 + ... + 5006.

It is an arithmetic number, because the mean of its divisors is an integer number (10008).

2³⁰⁰²¹ is an apocalyptic number.

It is an amenable number.

30021 is a deficient number, since it is larger than the sum of its proper divisors (10011).

30021 is a wasteful number, since it uses less digits than its factorization.

30021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10010.

The product of its (nonzero) digits is 6, while the sum is 6.

The square root of 30021 is about 173.2656919301. The cubic root of 30021 is about 31.0795735777.

Adding to 30021 its reverse (12003), we get a palindrome (42024).

It can be divided in two parts, 3002 and 1, that added together give a palindrome (3003).

The spelling of 30021 in words is "thirty thousand, twenty-one".