21124755 has 12 divisors (see below), whose sum is σ = 36616320. Its totient is φ = 11266512.

The previous prime is 21124711. The next prime is 21124759. The reversal of 21124755 is 55742112.

It is not a de Polignac number, because 21124755 - 2⁷ = 21124627 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21124759) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 234675 + ... + 234764.

It is an arithmetic number, because the mean of its divisors is an integer number (3051360).

Almost surely, 2^21124755 is an apocalyptic number.

21124755 is a deficient number, since it is larger than the sum of its proper divisors (15491565).

21124755 is a wasteful number, since it uses less digits than its factorization.

21124755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 469450 (or 469447 counting only the distinct ones).

The product of its digits is 2800, while the sum is 27.

The square root of 21124755 is about 4596.1674251489. The cubic root of 21124755 is about 276.4376720014.

Adding to 21124755 its reverse (55742112), we get a palindrome (76866867).

The spelling of 21124755 in words is "twenty-one million, one hundred twenty-four thousand, seven hundred fifty-five".