21412530 has 72 divisors (see below), whose sum is σ = 57582252. Its totient is φ = 5518656.

The previous prime is 21412513. The next prime is 21412549. The reversal of 21412530 is 3521412.

It can be written as a sum of positive squares in 2 ways, for example, as 21372129 + 40401 = 4623^2 + 201^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 319557 + ... + 319623.

Almost surely, 2^21412530 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21412530, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28791126).

21412530 is an abundant number, since it is smaller than the sum of its proper divisors (36169722).

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

21412530 is a wasteful number, since it uses less digits than its factorization.

21412530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200 (or 130 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21412530 is about 4627.3675021550. The cubic root of 21412530 is about 277.6872853084.

Adding to 21412530 its reverse (3521412), we get a palindrome (24933942).

The spelling of 21412530 in words is "twenty-one million, four hundred twelve thousand, five hundred thirty".