21000424 has 16 divisors (see below), whose sum is σ = 39456000. Its totient is φ = 10478832.

The previous prime is 21000407. The next prime is 21000433. The reversal of 21000424 is 42400012.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1977 + ... + 6775.

It is an arithmetic number, because the mean of its divisors is an integer number (2466000).

Almost surely, 2^21000424 is an apocalyptic number.

It is an amenable number.

21000424 is a deficient number, since it is larger than the sum of its proper divisors (18455576).

21000424 is a wasteful number, since it uses less digits than its factorization.

21000424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5352 (or 5348 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 13.

The square root of 21000424 is about 4582.6219569151. The cubic root of 21000424 is about 275.8942744254.

Adding to 21000424 its reverse (42400012), we get a palindrome (63400436).

The spelling of 21000424 in words is "twenty-one million, four hundred twenty-four", and thus it is an aban number.