21317608 has 32 divisors (see below), whose sum is σ = 43666560. Its totient is φ = 9696960.

The previous prime is 21317539. The next prime is 21317623. The reversal of 21317608 is 80671312.

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, 5941 + ... + 8827.

It is an arithmetic number, because the mean of its divisors is an integer number (1364580).

Almost surely, 2^21317608 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21317608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21833280).

21317608 is an abundant number, since it is smaller than the sum of its proper divisors (22348952).

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

21317608 is a wasteful number, since it uses less digits than its factorization.

21317608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2977 (or 2973 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21317608 is about 4617.0995224275. The cubic root of 21317608 is about 277.2763471321.

The spelling of 21317608 in words is "twenty-one million, three hundred seventeen thousand, six hundred eight".