21155124 has 24 divisors (see below), whose sum is σ = 51508800. Its totient is φ = 6745024.

The previous prime is 21155119. The next prime is 21155131. The reversal of 21155124 is 42155112.

It is a self number, because there is not a number n which added to its sum of digits gives 21155124.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 38049 + ... + 38600.

It is an arithmetic number, because the mean of its divisors is an integer number (2146200).

Almost surely, 2^21155124 is an apocalyptic number.

It is an amenable number.

21155124 is an abundant number, since it is smaller than the sum of its proper divisors (30353676).

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

21155124 is a wasteful number, since it uses less digits than its factorization.

21155124 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76679 (or 76677 counting only the distinct ones).

The product of its digits is 400, while the sum is 21.

The square root of 21155124 is about 4599.4699694639. The cubic root of 21155124 is about 276.5700777329.

It can be divided in two parts, 211551 and 24, that added together give a triangular number (211575 = T₆₅₀).

The spelling of 21155124 in words is "twenty-one million, one hundred fifty-five thousand, one hundred twenty-four".