21170253 has 32 divisors (see below), whose sum is σ = 33094656. Its totient is φ = 11916288.

The previous prime is 21170251. The next prime is 21170269. The reversal of 21170253 is 35207112.

It is not a de Polignac number, because 21170253 - 2¹ = 21170251 is a prime.

It is a super-2 number, since 2×21170253² = 896359224168018, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21170251) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 24100 + ... + 24962.

It is an arithmetic number, because the mean of its divisors is an integer number (1034208).

Almost surely, 2^21170253 is an apocalyptic number.

It is an amenable number.

21170253 is a deficient number, since it is larger than the sum of its proper divisors (11924403).

21170253 is a wasteful number, since it uses less digits than its factorization.

21170253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 933.

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 21170253 is about 4601.1143215530. The cubic root of 21170253 is about 276.6359913410.

Adding to 21170253 its reverse (35207112), we get a palindrome (56377365).

The spelling of 21170253 in words is "twenty-one million, one hundred seventy thousand, two hundred fifty-three".