21285008 has 10 divisors (see below), whose sum is σ = 41239734. Its totient is φ = 10642496.

The previous prime is 21285007. The next prime is 21285013. The reversal of 21285008 is 80058212.

It can be written as a sum of positive squares in only one way, i.e., 16908544 + 4376464 = 4112^2 + 2092^2 .

It is not an unprimeable number, because it can be changed into a prime (21285007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 665141 + ... + 665172.

Almost surely, 2^21285008 is an apocalyptic number.

It is an amenable number.

21285008 is a deficient number, since it is larger than the sum of its proper divisors (19954726).

21285008 is a wasteful number, since it uses less digits than its factorization.

21285008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1330321 (or 1330315 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 21285008 is about 4613.5678167769. The cubic root of 21285008 is about 277.1349331959.

The spelling of 21285008 in words is "twenty-one million, two hundred eighty-five thousand, eight".