21533875 has 16 divisors (see below), whose sum is σ = 29319264. Its totient is φ = 15660000.

The previous prime is 21533861. The next prime is 21533887. The reversal of 21533875 is 57833512.

It is not a de Polignac number, because 21533875 - 2⁵ = 21533843 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21533875.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 6456 + ... + 9205.

It is an arithmetic number, because the mean of its divisors is an integer number (1832454).

Almost surely, 2^21533875 is an apocalyptic number.

21533875 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21533875 is a deficient number, since it is larger than the sum of its proper divisors (7785389).

21533875 is a wasteful number, since it uses less digits than its factorization.

21533875 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15687 (or 15677 counting only the distinct ones).

The product of its digits is 25200, while the sum is 34.

The square root of 21533875 is about 4640.4606452377. The cubic root of 21533875 is about 278.2108496498.

The spelling of 21533875 in words is "twenty-one million, five hundred thirty-three thousand, eight hundred seventy-five".