21317788 has 12 divisors (see below), whose sum is σ = 37338840. Its totient is φ = 10649552.

The previous prime is 21317759. The next prime is 21317833. The reversal of 21317788 is 88771312.

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, 6570 + ... + 9262.

It is an arithmetic number, because the mean of its divisors is an integer number (3111570).

Almost surely, 2^21317788 is an apocalyptic number.

It is an amenable number.

21317788 is a deficient number, since it is larger than the sum of its proper divisors (16021052).

21317788 is a wasteful number, since it uses less digits than its factorization.

21317788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4676 (or 4674 counting only the distinct ones).

The product of its digits is 18816, while the sum is 37.

The square root of 21317788 is about 4617.1190151435. The cubic root of 21317788 is about 277.2771275449.

The spelling of 21317788 in words is "twenty-one million, three hundred seventeen thousand, seven hundred eighty-eight".