21012424 has 16 divisors (see below), whose sum is σ = 39449520. Its totient is φ = 10492560.

The previous prime is 21012421. The next prime is 21012449. The reversal of 21012424 is 42421012.

It is a junction number, because it is equal to n+sod(n) for n = 21012398 and 21012407.

It is not an unprimeable number, because it can be changed into a prime (21012421) 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 3 ways as a sum of consecutive naturals, for example, 8247 + ... + 10489.

It is an arithmetic number, because the mean of its divisors is an integer number (2465595).

Almost surely, 2^21012424 is an apocalyptic number.

It is an amenable number.

21012424 is a deficient number, since it is larger than the sum of its proper divisors (18437096).

21012424 is a wasteful number, since it uses less digits than its factorization.

21012424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3420 (or 3416 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 21012424 is about 4583.9310640541. The cubic root of 21012424 is about 275.9468146485.

Adding to 21012424 its reverse (42421012), we get a palindrome (63433436).

The spelling of 21012424 in words is "twenty-one million, twelve thousand, four hundred twenty-four".