21133257 has 8 divisors (see below), whose sum is σ = 29149440. Its totient is φ = 13602960.

The previous prime is 21133243. The next prime is 21133283. The reversal of 21133257 is 75233112.

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

It is not a de Polignac number, because 21133257 - 2⁴ = 21133241 is a prime.

It is a super-2 number, since 2×21133257² = 893229102856098, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21133237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 121369 + ... + 121542.

It is an arithmetic number, because the mean of its divisors is an integer number (3643680).

Almost surely, 2^21133257 is an apocalyptic number.

It is an amenable number.

21133257 is a deficient number, since it is larger than the sum of its proper divisors (8016183).

21133257 is a wasteful number, since it uses less digits than its factorization.

21133257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242943.

The product of its digits is 1260, while the sum is 24.

The square root of 21133257 is about 4597.0922331404. The cubic root of 21133257 is about 276.4747526343.

Adding to 21133257 its reverse (75233112), we get a palindrome (96366369).

The spelling of 21133257 in words is "twenty-one million, one hundred thirty-three thousand, two hundred fifty-seven".