21287008 has 24 divisors (see below), whose sum is σ = 42307272. Its totient is φ = 10542336.

The previous prime is 21286999. The next prime is 21287027. The reversal of 21287008 is 80078212.

It is a congruent number.

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, 316 + ... + 6532.

It is an arithmetic number, because the mean of its divisors is an integer number (1762803).

Almost surely, 2^21287008 is an apocalyptic number.

It is an amenable number.

21287008 is a deficient number, since it is larger than the sum of its proper divisors (21020264).

21287008 is a wasteful number, since it uses less digits than its factorization.

21287008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6334 (or 6326 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 28.

The square root of 21287008 is about 4613.7845636744. The cubic root of 21287008 is about 277.1436130533.

The spelling of 21287008 in words is "twenty-one million, two hundred eighty-seven thousand, eight".