21655165550 has 48 divisors (see below), whose sum is σ = 40587402240. Its totient is φ = 8595838560.

The previous prime is 21655165549. The next prime is 21655165601. The reversal of 21655165550 is 5556155612.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21655165498 and 21655165507.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6001847 + ... + 6005453.

It is an arithmetic number, because the mean of its divisors is an integer number (845570880).

Almost surely, 2^21655165550 is an apocalyptic number.

21655165550 is a deficient number, since it is larger than the sum of its proper divisors (18932236690).

21655165550 is a wasteful number, since it uses less digits than its factorization.

21655165550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4505 (or 4500 counting only the distinct ones).

The product of its (nonzero) digits is 225000, while the sum is 41.

The spelling of 21655165550 in words is "twenty-one billion, six hundred fifty-five million, one hundred sixty-five thousand, five hundred fifty".