21154253 has 4 divisors (see below), whose sum is σ = 21883740. Its totient is φ = 20424768.

The previous prime is 21154207. The next prime is 21154283. The reversal of 21154253 is 35245112.

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 4401604 + 16752649 = 2098^2 + 4093^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154253 - 2²⁰ = 20105677 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 (21154283) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 364700 + ... + 364757.

It is an arithmetic number, because the mean of its divisors is an integer number (5470935).

Almost surely, 2^21154253 is an apocalyptic number.

It is an amenable number.

21154253 is a deficient number, since it is larger than the sum of its proper divisors (729487).

21154253 is an equidigital number, since it uses as much as digits as its factorization.

21154253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 729486.

The product of its digits is 1200, while the sum is 23.

The square root of 21154253 is about 4599.3752836663. The cubic root of 21154253 is about 276.5662820277.

Adding to 21154253 its reverse (35245112), we get a palindrome (56399365).

The spelling of 21154253 in words is "twenty-one million, one hundred fifty-four thousand, two hundred fifty-three".