21330621 has 40 divisors (see below), whose sum is σ = 35126784. Its totient is φ = 12817440.

The previous prime is 21330607. The next prime is 21330629. The reversal of 21330621 is 12603312.

21330621 is a `hidden beast` number, since 2 + 13 + 30 + 621 = 666.

It is not a de Polignac number, because 21330621 - 2¹⁵ = 21297853 is a prime.

It is a Curzon number.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 21330594 and 21330603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21330629) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 49276 + ... + 49706.

Almost surely, 2^21330621 is an apocalyptic number.

It is an amenable number.

21330621 is a deficient number, since it is larger than the sum of its proper divisors (13796163).

21330621 is a wasteful number, since it uses less digits than its factorization.

21330621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 503 (or 494 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21330621 is about 4618.5085254874. The cubic root of 21330621 is about 277.3327553240.

Adding to 21330621 its reverse (12603312), we get a palindrome (33933933).

The spelling of 21330621 in words is "twenty-one million, three hundred thirty thousand, six hundred twenty-one".