21611253 has 8 divisors (see below), whose sum is σ = 28952416. Its totient is φ = 14338800.

The previous prime is 21611251. The next prime is 21611257. The reversal of 21611253 is 35211612.

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

It is not a de Polignac number, because 21611253 - 2¹ = 21611251 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 (21611251) 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 7 ways as a sum of consecutive naturals, for example, 16438 + ... + 17703.

It is an arithmetic number, because the mean of its divisors is an integer number (3619052).

Almost surely, 2^21611253 is an apocalyptic number.

It is an amenable number.

21611253 is a deficient number, since it is larger than the sum of its proper divisors (7341163).

21611253 is a wasteful number, since it uses less digits than its factorization.

21611253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34355.

The product of its digits is 360, while the sum is 21.

The square root of 21611253 is about 4648.7904878581. The cubic root of 21611253 is about 278.5436843976.

Adding to 21611253 its reverse (35211612), we get a palindrome (56822865).

The spelling of 21611253 in words is "twenty-one million, six hundred eleven thousand, two hundred fifty-three".