21105505608 has 32 divisors (see below), whose sum is σ = 57560470560. Its totient is φ = 6395607680.

The previous prime is 21105505607. The next prime is 21105505609. The reversal of 21105505608 is 80650550112.

It is an interprime number because it is at equal distance from previous prime (21105505607) and next prime (21105505609).

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21105505607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39972285 + ... + 39972812.

It is an arithmetic number, because the mean of its divisors is an integer number (1798764705).

Almost surely, 2^21105505608 is an apocalyptic number.

It is an amenable number.

21105505608 is an abundant number, since it is smaller than the sum of its proper divisors (36454964952).

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

21105505608 is a wasteful number, since it uses less digits than its factorization.

21105505608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79945117 (or 79945113 counting only the distinct ones).

The product of its (nonzero) digits is 12000, while the sum is 33.

The spelling of 21105505608 in words is "twenty-one billion, one hundred five million, five hundred five thousand, six hundred eight".