21025253 has 4 divisors (see below), whose sum is σ = 21178860. Its totient is φ = 20871648.

The previous prime is 21025217. The next prime is 21025273. The reversal of 21025253 is 35252012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 17156164 + 3869089 = 4142^2 + 1967^2 .

It is a cyclic number.

It is not a de Polignac number, because 21025253 - 2⁶ = 21025189 is a prime.

It is a super-2 number, since 2×21025253² = 884122527428018, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21025273) 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, 76598 + ... + 76871.

It is an arithmetic number, because the mean of its divisors is an integer number (5294715).

Almost surely, 2^21025253 is an apocalyptic number.

It is an amenable number.

21025253 is a deficient number, since it is larger than the sum of its proper divisors (153607).

21025253 is a wasteful number, since it uses less digits than its factorization.

21025253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153606.

The product of its (nonzero) digits is 600, while the sum is 20.

The square root of 21025253 is about 4585.3301953076. The cubic root of 21025253 is about 276.0029624061.

Adding to 21025253 its reverse (35252012), we get a palindrome (56277265).

The spelling of 21025253 in words is "twenty-one million, twenty-five thousand, two hundred fifty-three".