21409530 has 32 divisors (see below), whose sum is σ = 53042688. Its totient is φ = 5524800.

The previous prime is 21409529. The next prime is 21409541. The reversal of 21409530 is 3590412.

It is a self number, because there is not a number n which added to its sum of digits gives 21409530.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10581 + ... + 12440.

It is an arithmetic number, because the mean of its divisors is an integer number (1657584).

Almost surely, 2^21409530 is an apocalyptic number.

21409530 is an abundant number, since it is smaller than the sum of its proper divisors (31633158).

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

21409530 is a wasteful number, since it uses less digits than its factorization.

21409530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23062.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21409530 is about 4627.0433324100. The cubic root of 21409530 is about 277.6743162545.

Adding to 21409530 its reverse (3590412), we get a palindrome (24999942).

The spelling of 21409530 in words is "twenty-one million, four hundred nine thousand, five hundred thirty".