21204030 has 16 divisors (see below), whose sum is σ = 50889744. Its totient is φ = 5654400.

The previous prime is 21204013. The next prime is 21204037. The reversal of 21204030 is 3040212.

It is a super-2 number, since 2×21204030² = 899221776481800, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21203997 and 21204015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204037) 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, 353371 + ... + 353430.

It is an arithmetic number, because the mean of its divisors is an integer number (3180609).

Almost surely, 2^21204030 is an apocalyptic number.

21204030 is an abundant number, since it is smaller than the sum of its proper divisors (29685714).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21204030 is a wasteful number, since it uses less digits than its factorization.

21204030 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 706811.

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 21204030 is about 4604.7833825273. The cubic root of 21204030 is about 276.7830368028.

Adding to 21204030 its reverse (3040212), we get a palindrome (24244242).

The spelling of 21204030 in words is "twenty-one million, two hundred four thousand, thirty".