21443564 has 12 divisors (see below), whose sum is σ = 37571688. Its totient is φ = 10708800.

The previous prime is 21443561. The next prime is 21443573. The reversal of 21443564 is 46534412.

It is not an unprimeable number, because it can be changed into a prime (21443561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1124 + ... + 6644.

It is an arithmetic number, because the mean of its divisors is an integer number (3130974).

Almost surely, 2^21443564 is an apocalyptic number.

It is an amenable number.

21443564 is a deficient number, since it is larger than the sum of its proper divisors (16128124).

21443564 is a wasteful number, since it uses less digits than its factorization.

21443564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6496 (or 6494 counting only the distinct ones).

The product of its digits is 11520, while the sum is 29.

The square root of 21443564 is about 4630.7195985073. The cubic root of 21443564 is about 277.8213748223.

Adding to 21443564 its reverse (46534412), we get a palindrome (67977976).

The spelling of 21443564 in words is "twenty-one million, four hundred forty-three thousand, five hundred sixty-four".