21254521 has 4 divisors (see below), whose sum is σ = 22373200. Its totient is φ = 20135844.

The previous prime is 21254491. The next prime is 21254567. The reversal of 21254521 is 12545212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21254521 - 2⁷ = 21254393 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21254492 and 21254501.

It is not an unprimeable number, because it can be changed into a prime (21254581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 559311 + ... + 559348.

It is an arithmetic number, because the mean of its divisors is an integer number (5593300).

Almost surely, 2^21254521 is an apocalyptic number.

It is an amenable number.

21254521 is a deficient number, since it is larger than the sum of its proper divisors (1118679).

21254521 is a wasteful number, since it uses less digits than its factorization.

21254521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1118678.

The product of its digits is 800, while the sum is 22.

The square root of 21254521 is about 4610.2625738671. The cubic root of 21254521 is about 277.0025544213.

Adding to 21254521 its reverse (12545212), we get a palindrome (33799733).

The spelling of 21254521 in words is "twenty-one million, two hundred fifty-four thousand, five hundred twenty-one".