21504253 has 8 divisors (see below), whose sum is σ = 21951488. Its totient is φ = 21060864.

The previous prime is 21504251. The next prime is 21504271. The reversal of 21504253 is 35240512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21504253 - 2¹ = 21504251 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 (21504251) 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 7 ways as a sum of consecutive naturals, for example, 12100 + ... + 13762.

It is an arithmetic number, because the mean of its divisors is an integer number (2743936).

Almost surely, 2^21504253 is an apocalyptic number.

It is an amenable number.

21504253 is a deficient number, since it is larger than the sum of its proper divisors (447235).

21504253 is a wasteful number, since it uses less digits than its factorization.

21504253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1923.

The product of its (nonzero) digits is 1200, while the sum is 22.

The square root of 21504253 is about 4637.2678378545. The cubic root of 21504253 is about 278.0832221555.

Adding to 21504253 its reverse (35240512), we get a palindrome (56744765).

The spelling of 21504253 in words is "twenty-one million, five hundred four thousand, two hundred fifty-three".