21033257 has 8 divisors (see below), whose sum is σ = 24076032. Its totient is φ = 18000000.

The previous prime is 21033239. The next prime is 21033263. The reversal of 21033257 is 75233012.

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

It is a cyclic number.

It is not a de Polignac number, because 21033257 - 2⁶ = 21033193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21033277) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3257 + ... + 7257.

It is an arithmetic number, because the mean of its divisors is an integer number (3009504).

Almost surely, 2^21033257 is an apocalyptic number.

It is an amenable number.

21033257 is a deficient number, since it is larger than the sum of its proper divisors (3042775).

21033257 is an equidigital number, since it uses as much as digits as its factorization.

21033257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4759.

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 21033257 is about 4586.2028956425. The cubic root of 21033257 is about 276.0379813655.

Adding to 21033257 its reverse (75233012), we get a palindrome (96266269).

The spelling of 21033257 in words is "twenty-one million, thirty-three thousand, two hundred fifty-seven".