21361661636 has 24 divisors (see below), whose sum is σ = 42734684160. Its totient is φ = 9152563392.

The previous prime is 21361661621. The next prime is 21361661663. The reversal of 21361661636 is 63616616312.

It is a junction number, because it is equal to n+sod(n) for n = 21361661593 and 21361661602.

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, 7805 + ... + 206843.

It is an arithmetic number, because the mean of its divisors is an integer number (1780611840).

Almost surely, 2^21361661636 is an apocalyptic number.

It is an amenable number.

21361661636 is an abundant number, since it is smaller than the sum of its proper divisors (21373022524).

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

21361661636 is a wasteful number, since it uses less digits than its factorization.

21361661636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202883 (or 202881 counting only the distinct ones).

The product of its digits is 139968, while the sum is 41.

The spelling of 21361661636 in words is "twenty-one billion, three hundred sixty-one million, six hundred sixty-one thousand, six hundred thirty-six".