21564290 has 16 divisors (see below), whose sum is σ = 42344640. Its totient is φ = 7841520.

The previous prime is 21564289. The next prime is 21564299. The reversal of 21564290 is 9246512.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21564299) 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, 97910 + ... + 98129.

It is an arithmetic number, because the mean of its divisors is an integer number (2646540).

Almost surely, 2^21564290 is an apocalyptic number.

21564290 is a deficient number, since it is larger than the sum of its proper divisors (20780350).

21564290 is a wasteful number, since it uses less digits than its factorization.

21564290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196057.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 21564290 is about 4643.7366419727. The cubic root of 21564290 is about 278.3417720877.

It can be divided in two parts, 2156 and 4290, that added together give a palindrome (6446).

The spelling of 21564290 in words is "twenty-one million, five hundred sixty-four thousand, two hundred ninety".