21491133 has 4 divisors (see below), whose sum is σ = 28654848. Its totient is φ = 14327420.

The previous prime is 21491101. The next prime is 21491149. The reversal of 21491133 is 33119412.

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 21491133 - 2⁵ = 21491101 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21491633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3581853 + ... + 3581858.

It is an arithmetic number, because the mean of its divisors is an integer number (7163712).

Almost surely, 2^21491133 is an apocalyptic number.

It is an amenable number.

21491133 is a deficient number, since it is larger than the sum of its proper divisors (7163715).

21491133 is an equidigital number, since it uses as much as digits as its factorization.

21491133 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7163714.

The product of its digits is 648, while the sum is 24.

The square root of 21491133 is about 4635.8529959437. The cubic root of 21491133 is about 278.0266566920.

The spelling of 21491133 in words is "twenty-one million, four hundred ninety-one thousand, one hundred thirty-three".