30020821 has 4 divisors (see below), whose sum is σ = 30330412. Its totient is φ = 29711232.

The previous prime is 30020813. The next prime is 30020831. The reversal of 30020821 is 12802003.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6604900 + 23415921 = 2570^2 + 4839^2 .

It is a cyclic number.

It is not a de Polignac number, because 30020821 - 2³ = 30020813 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 30020795 and 30020804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (30020831) 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, 154650 + ... + 154843.

It is an arithmetic number, because the mean of its divisors is an integer number (7582603).

Almost surely, 2^30020821 is an apocalyptic number.

It is an amenable number.

30020821 is a deficient number, since it is larger than the sum of its proper divisors (309591).

30020821 is an equidigital number, since it uses as much as digits as its factorization.

30020821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309590.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 30020821 is about 5479.1259339424. The cubic root of 30020821 is about 310.7951180696.

Adding to 30020821 its reverse (12802003), we get a palindrome (42822824).

The spelling of 30020821 in words is "thirty million, twenty thousand, eight hundred twenty-one".