21645230 has 32 divisors (see below), whose sum is σ = 39960000. Its totient is φ = 8439552.

The previous prime is 21645229. The next prime is 21645257. The reversal of 21645230 is 3254612.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21645196 and 21645205.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 108671 + ... + 108869.

It is an arithmetic number, because the mean of its divisors is an integer number (1248750).

Almost surely, 2^21645230 is an apocalyptic number.

21645230 is a deficient number, since it is larger than the sum of its proper divisors (18314770).

21645230 is a wasteful number, since it uses less digits than its factorization.

21645230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 428.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21645230 is about 4652.4434440410. The cubic root of 21645230 is about 278.6895825140.

Adding to 21645230 its reverse (3254612), we get a palindrome (24899842).

The spelling of 21645230 in words is "twenty-one million, six hundred forty-five thousand, two hundred thirty".