21663126 has 20 divisors (see below), whose sum is σ = 48541812. Its totient is φ = 7220988.

The previous prime is 21663119. The next prime is 21663127. The reversal of 21663126 is 62136612.

21663126 is a `hidden beast` number, since 2 + 1 + 6 + 631 + 26 = 666.

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

It is a nude number because it is divisible by every one of its digits.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21663126.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21663127) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 66700 + ... + 67023.

Almost surely, 2^21663126 is an apocalyptic number.

21663126 is an abundant number, since it is smaller than the sum of its proper divisors (26878686).

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

21663126 is a wasteful number, since it uses less digits than its factorization.

21663126 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133737 (or 133728 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 21663126 is about 4654.3663371076. The cubic root of 21663126 is about 278.7663670201.

Adding to 21663126 its reverse (62136612), we get a palindrome (83799738).

The spelling of 21663126 in words is "twenty-one million, six hundred sixty-three thousand, one hundred twenty-six".