21312124 has 12 divisors (see below), whose sum is σ = 37590784. Its totient is φ = 10571904.

The previous prime is 21312121. The next prime is 21312149. The reversal of 21312124 is 42121312.

It is a junction number, because it is equal to n+sod(n) for n = 21312098 and 21312107.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312121) 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, 20469 + ... + 21484.

Almost surely, 2^21312124 is an apocalyptic number.

It is an amenable number.

21312124 is a deficient number, since it is larger than the sum of its proper divisors (16278660).

21312124 is a wasteful number, since it uses less digits than its factorization.

21312124 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42084 (or 42082 counting only the distinct ones).

The product of its digits is 96, while the sum is 16.

The square root of 21312124 is about 4616.5056048921. The cubic root of 21312124 is about 277.2525684496.

Adding to 21312124 its reverse (42121312), we get a palindrome (63433436).

The spelling of 21312124 in words is "twenty-one million, three hundred twelve thousand, one hundred twenty-four".