21533838 has 8 divisors (see below), whose sum is σ = 43067688. Its totient is φ = 7177944.

The previous prime is 21533807. The next prime is 21533843. The reversal of 21533838 is 83833512.

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

21533838 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 21533799 and 21533808.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1794481 + ... + 1794492.

It is an arithmetic number, because the mean of its divisors is an integer number (5383461).

Almost surely, 2^21533838 is an apocalyptic number.

21533838 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21533838 is a wasteful number, since it uses less digits than its factorization.

21533838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3588978.

The product of its digits is 17280, while the sum is 33.

The square root of 21533838 is about 4640.4566585628. The cubic root of 21533838 is about 278.2106903070.

The spelling of 21533838 in words is "twenty-one million, five hundred thirty-three thousand, eight hundred thirty-eight".