21217253560 has 32 divisors (see below), whose sum is σ = 47868932160. Its totient is φ = 8463770496.

The previous prime is 21217253537. The next prime is 21217253573. The reversal of 21217253560 is 6535271212.

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, 707979 + ... + 737338.

It is an arithmetic number, because the mean of its divisors is an integer number (1495904130).

Almost surely, 2^21217253560 is an apocalyptic number.

21217253560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21217253560 is an abundant number, since it is smaller than the sum of its proper divisors (26651678600).

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

21217253560 is a wasteful number, since it uses less digits than its factorization.

21217253560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1445695 (or 1445691 counting only the distinct ones).

The product of its (nonzero) digits is 25200, while the sum is 34.

The spelling of 21217253560 in words is "twenty-one billion, two hundred seventeen million, two hundred fifty-three thousand, five hundred sixty".