21563442 has 32 divisors (see below), whose sum is σ = 50443200. Its totient is φ = 6809184.

The previous prime is 21563419. The next prime is 21563449. The reversal of 21563442 is 24436512.

21563442 is a `hidden beast` number, since 21 + 5 + 634 + 4 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21563449) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9483 + ... + 11534.

It is an arithmetic number, because the mean of its divisors is an integer number (1576350).

Almost surely, 2^21563442 is an apocalyptic number.

21563442 is an abundant number, since it is smaller than the sum of its proper divisors (28879758).

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

21563442 is a wasteful number, since it uses less digits than its factorization.

21563442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21047 (or 21041 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 21563442 is about 4643.6453352942. The cubic root of 21563442 is about 278.3381235107.

Adding to 21563442 its reverse (24436512), we get a palindrome (45999954).

The spelling of 21563442 in words is "twenty-one million, five hundred sixty-three thousand, four hundred forty-two".