21609610521 has 8 divisors (see below), whose sum is σ = 28827742944. Its totient is φ = 14398942560.

The previous prime is 21609610513. The next prime is 21609610543. The reversal of 21609610521 is 12501690612.

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

It is not a de Polignac number, because 21609610521 - 2³ = 21609610513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21609610501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1859356 + ... + 1870941.

It is an arithmetic number, because the mean of its divisors is an integer number (3603467868).

Almost surely, 2^21609610521 is an apocalyptic number.

It is an amenable number.

21609610521 is a deficient number, since it is larger than the sum of its proper divisors (7218132423).

21609610521 is a wasteful number, since it uses less digits than its factorization.

21609610521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3732231.

The product of its (nonzero) digits is 6480, while the sum is 33.

The spelling of 21609610521 in words is "twenty-one billion, six hundred nine million, six hundred ten thousand, five hundred twenty-one".