21533124 has 12 divisors (see below), whose sum is σ = 50243984. Its totient is φ = 7177704.

The previous prime is 21533123. The next prime is 21533131. The reversal of 21533124 is 42133512.

It is a tau number, because it is divible by the number of its divisors (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21533124.

It is not an unprimeable number, because it can be changed into a prime (21533123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 897202 + ... + 897225.

Almost surely, 2^21533124 is an apocalyptic number.

It is an amenable number.

21533124 is an abundant number, since it is smaller than the sum of its proper divisors (28710860).

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

21533124 is a wasteful number, since it uses less digits than its factorization.

21533124 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1794434 (or 1794432 counting only the distinct ones).

The product of its digits is 720, while the sum is 21.

The square root of 21533124 is about 4640.3797258414. The cubic root of 21533124 is about 278.2076153848.

Adding to 21533124 its reverse (42133512), we get a palindrome (63666636).

The spelling of 21533124 in words is "twenty-one million, five hundred thirty-three thousand, one hundred twenty-four".