21610542561 has 8 divisors (see below), whose sum is σ = 30066841920. Its totient is φ = 13780635792.

The previous prime is 21610542497. The next prime is 21610542581. The reversal of 21610542561 is 16524501612.

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

It is not a de Polignac number, because 21610542561 - 2⁶ = 21610542497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21610542581) 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, 156598066 + ... + 156598203.

It is an arithmetic number, because the mean of its divisors is an integer number (3758355240).

Almost surely, 2^21610542561 is an apocalyptic number.

It is an amenable number.

21610542561 is a deficient number, since it is larger than the sum of its proper divisors (8456299359).

21610542561 is a wasteful number, since it uses less digits than its factorization.

21610542561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313196295.

The product of its (nonzero) digits is 14400, while the sum is 33.

The spelling of 21610542561 in words is "twenty-one billion, six hundred ten million, five hundred forty-two thousand, five hundred sixty-one".