21645530 has 16 divisors (see below), whose sum is σ = 40656384. Its totient is φ = 8281680.

The previous prime is 21645527. The next prime is 21645551. The reversal of 21645530 is 3554612.

It is a self number, because there is not a number n which added to its sum of digits gives 21645530.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46826 + ... + 47285.

It is an arithmetic number, because the mean of its divisors is an integer number (2541024).

Almost surely, 2^21645530 is an apocalyptic number.

21645530 is a deficient number, since it is larger than the sum of its proper divisors (19010854).

21645530 is a wasteful number, since it uses less digits than its factorization.

21645530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94141.

The product of its (nonzero) digits is 3600, while the sum is 26.

The square root of 21645530 is about 4652.4756850520. The cubic root of 21645530 is about 278.6908700415.

The spelling of 21645530 in words is "twenty-one million, six hundred forty-five thousand, five hundred thirty".