21030321 has 32 divisors (see below), whose sum is σ = 32215680. Its totient is φ = 12096000.

The previous prime is 21030313. The next prime is 21030329. The reversal of 21030321 is 12303012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21030313) and next prime (21030329).

It is not a de Polignac number, because 21030321 - 2³ = 21030313 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21030297 and 21030306.

It is not an unprimeable number, because it can be changed into a prime (21030329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 74701 + ... + 74981.

It is an arithmetic number, because the mean of its divisors is an integer number (1006740).

Almost surely, 2^21030321 is an apocalyptic number.

It is an amenable number.

21030321 is a deficient number, since it is larger than the sum of its proper divisors (11185359).

21030321 is a wasteful number, since it uses less digits than its factorization.

21030321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 417.

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21030321 is about 4585.8827939667. The cubic root of 21030321 is about 276.0251368620.

Adding to 21030321 its reverse (12303012), we get a palindrome (33333333).

The spelling of 21030321 in words is "twenty-one million, thirty thousand, three hundred twenty-one".