21445530 has 16 divisors (see below), whose sum is σ = 51469344. Its totient is φ = 5718800.

The previous prime is 21445513. The next prime is 21445537. The reversal of 21445530 is 3554412.

It is a self number, because there is not a number n which added to its sum of digits gives 21445530.

It is not an unprimeable number, because it can be changed into a prime (21445537) 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, 357396 + ... + 357455.

It is an arithmetic number, because the mean of its divisors is an integer number (3216834).

Almost surely, 2^21445530 is an apocalyptic number.

21445530 is an abundant number, since it is smaller than the sum of its proper divisors (30023814).

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

21445530 is a wasteful number, since it uses less digits than its factorization.

21445530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 714861.

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 21445530 is about 4630.9318716647. The cubic root of 21445530 is about 277.8298650175.

Adding to 21445530 its reverse (3554412), we get a palindrome (24999942).

The spelling of 21445530 in words is "twenty-one million, four hundred forty-five thousand, five hundred thirty".