21254663 has 4 divisors (see below), whose sum is σ = 21355608. Its totient is φ = 21153720.

The previous prime is 21254647. The next prime is 21254677. The reversal of 21254663 is 36645212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21254663 - 2⁴ = 21254647 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21254633) 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, 50156 + ... + 50577.

It is an arithmetic number, because the mean of its divisors is an integer number (5338902).

Almost surely, 2^21254663 is an apocalyptic number.

21254663 is a deficient number, since it is larger than the sum of its proper divisors (100945).

21254663 is a wasteful number, since it uses less digits than its factorization.

21254663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100944.

The product of its digits is 8640, while the sum is 29.

The square root of 21254663 is about 4610.2779742658. The cubic root of 21254663 is about 277.0031712983.

Adding to 21254663 its reverse (36645212), we get a palindrome (57899875).

The spelling of 21254663 in words is "twenty-one million, two hundred fifty-four thousand, six hundred sixty-three".