21123253 has 8 divisors (see below), whose sum is σ = 21384000. Its totient is φ = 20864448.

The previous prime is 21123211. The next prime is 21123287. The reversal of 21123253 is 35232112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21123253 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21123253.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123293) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35325 + ... + 35917.

It is an arithmetic number, because the mean of its divisors is an integer number (2673000).

Almost surely, 2^21123253 is an apocalyptic number.

It is an amenable number.

21123253 is a deficient number, since it is larger than the sum of its proper divisors (260747).

21123253 is a wasteful number, since it uses less digits than its factorization.

21123253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 971.

The product of its digits is 360, while the sum is 19.

The square root of 21123253 is about 4596.0040252376. The cubic root of 21123253 is about 276.4311201428.

Adding to 21123253 its reverse (35232112), we get a palindrome (56355365).

The spelling of 21123253 in words is "twenty-one million, one hundred twenty-three thousand, two hundred fifty-three".