21253351 has 4 divisors (see below), whose sum is σ = 24289552. Its totient is φ = 18217152.

The previous prime is 21253339. The next prime is 21253361. The reversal of 21253351 is 15335212.

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

It is a cyclic number.

It is not a de Polignac number, because 21253351 - 2⁵ = 21253319 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253301) 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, 1518090 + ... + 1518103.

It is an arithmetic number, because the mean of its divisors is an integer number (6072388).

Almost surely, 2^21253351 is an apocalyptic number.

21253351 is a deficient number, since it is larger than the sum of its proper divisors (3036201).

21253351 is an equidigital number, since it uses as much as digits as its factorization.

21253351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3036200.

The product of its digits is 900, while the sum is 22.

The square root of 21253351 is about 4610.1356813005. The cubic root of 21253351 is about 276.9974715978.

Adding to 21253351 its reverse (15335212), we get a palindrome (36588563).

It can be divided in two parts, 2125 and 3351, that added together give a square (5476 = 74²).

The spelling of 21253351 in words is "twenty-one million, two hundred fifty-three thousand, three hundred fifty-one".