21004872 has 32 divisors (see below), whose sum is σ = 60014400. Its totient is φ = 6001344.

The previous prime is 21004847. The next prime is 21004883. The reversal of 21004872 is 27840012.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62347 + ... + 62682.

It is an arithmetic number, because the mean of its divisors is an integer number (1875450).

Almost surely, 2^21004872 is an apocalyptic number.

It is an amenable number.

21004872 is an abundant number, since it is smaller than the sum of its proper divisors (39009528).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21004872 is a wasteful number, since it uses less digits than its factorization.

21004872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125045 (or 125041 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 21004872 is about 4583.1072429085. The cubic root of 21004872 is about 275.9137516687.

Adding to 21004872 its reverse (27840012), we get a palindrome (48844884).

The spelling of 21004872 in words is "twenty-one million, four thousand, eight hundred seventy-two".