21251953 has 4 divisors (see below), whose sum is σ = 21295728. Its totient is φ = 21208180.

The previous prime is 21251941. The next prime is 21251987. The reversal of 21251953 is 35915212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21251953 - 2⁹ = 21251441 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21251903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21151 + ... + 22132.

It is an arithmetic number, because the mean of its divisors is an integer number (5323932).

Almost surely, 2^21251953 is an apocalyptic number.

It is an amenable number.

21251953 is a deficient number, since it is larger than the sum of its proper divisors (43775).

21251953 is an equidigital number, since it uses as much as digits as its factorization.

21251953 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43774.

The product of its digits is 2700, while the sum is 28.

The square root of 21251953 is about 4609.9840563716. The cubic root of 21251953 is about 276.9913980308.

The spelling of 21251953 in words is "twenty-one million, two hundred fifty-one thousand, nine hundred fifty-three".