21018008 has 16 divisors (see below), whose sum is σ = 42991560. Its totient is φ = 9553600.

The previous prime is 21017993. The next prime is 21018043. The reversal of 21018008 is 80081012.

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, 119333 + ... + 119508.

Almost surely, 2^21018008 is an apocalyptic number.

It is an amenable number.

21018008 is an abundant number, since it is smaller than the sum of its proper divisors (21973552).

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

21018008 is a wasteful number, since it uses less digits than its factorization.

21018008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238858 (or 238854 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 20.

The square root of 21018008 is about 4584.5401077971. The cubic root of 21018008 is about 275.9712565460.

The spelling of 21018008 in words is "twenty-one million, eighteen thousand, eight".