21560420521 has 8 divisors (see below), whose sum is σ = 21785400000. Its totient is φ = 21336439440.

The previous prime is 21560420503. The next prime is 21560420543. The reversal of 21560420521 is 12502406512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21560420521 - 2⁷ = 21560420393 is a prime.

It is a super-2 number, since 2×21560420521² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21560420521.

It is not an unprimeable number, because it can be changed into a prime (21560820521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 206146 + ... + 292603.

It is an arithmetic number, because the mean of its divisors is an integer number (2723175000).

Almost surely, 2^21560420521 is an apocalyptic number.

It is an amenable number.

21560420521 is a deficient number, since it is larger than the sum of its proper divisors (224979479).

21560420521 is a wasteful number, since it uses less digits than its factorization.

21560420521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 499199.

The product of its (nonzero) digits is 4800, while the sum is 28.

The spelling of 21560420521 in words is "twenty-one billion, five hundred sixty million, four hundred twenty thousand, five hundred twenty-one".