21351253 has 16 divisors (see below), whose sum is σ = 26812800. Its totient is φ = 16516800.

The previous prime is 21351241. The next prime is 21351287. The reversal of 21351253 is 35215312.

It is a cyclic number.

It is not a de Polignac number, because 21351253 - 2⁹ = 21350741 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21351233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10543 + ... + 12403.

It is an arithmetic number, because the mean of its divisors is an integer number (1675800).

Almost surely, 2^21351253 is an apocalyptic number.

It is an amenable number.

21351253 is a deficient number, since it is larger than the sum of its proper divisors (5461547).

21351253 is a wasteful number, since it uses less digits than its factorization.

21351253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2028.

The product of its digits is 900, while the sum is 22.

The square root of 21351253 is about 4620.7416071449. The cubic root of 21351253 is about 277.4221430256.

Adding to 21351253 its reverse (35215312), we get a palindrome (56566565).

The spelling of 21351253 in words is "twenty-one million, three hundred fifty-one thousand, two hundred fifty-three".