21317687220 has 24 divisors (see below), whose sum is σ = 59689524384. Its totient is φ = 5684716576.

The previous prime is 21317687219. The next prime is 21317687243. The reversal of 21317687220 is 2278671312.

It is a congruent number.

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, 177647334 + ... + 177647453.

It is an arithmetic number, because the mean of its divisors is an integer number (2487063516).

Almost surely, 2^21317687220 is an apocalyptic number.

21317687220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21317687220 is an abundant number, since it is smaller than the sum of its proper divisors (38371837164).

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

21317687220 is a wasteful number, since it uses less digits than its factorization.

21317687220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355294799 (or 355294797 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 39.

The spelling of 21317687220 in words is "twenty-one billion, three hundred seventeen million, six hundred eighty-seven thousand, two hundred twenty".