21008924 has 6 divisors (see below), whose sum is σ = 36765624. Its totient is φ = 10504460.

The previous prime is 21008903. The next prime is 21008941. The reversal of 21008924 is 42980012.

It is a junction number, because it is equal to n+sod(n) for n = 21008893 and 21008902.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2626112 + ... + 2626119.

It is an arithmetic number, because the mean of its divisors is an integer number (6127604).

Almost surely, 2^21008924 is an apocalyptic number.

It is an amenable number.

21008924 is a deficient number, since it is larger than the sum of its proper divisors (15756700).

21008924 is a wasteful number, since it uses less digits than its factorization.

21008924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5252235 (or 5252233 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21008924 is about 4583.5492797613. The cubic root of 21008924 is about 275.9314924836.

Adding to 21008924 its reverse (42980012), we get a palindrome (63988936).

The spelling of 21008924 in words is "twenty-one million, eight thousand, nine hundred twenty-four".