21663451550 has 48 divisors (see below), whose sum is σ = 44105010432. Its totient is φ = 7867670400.

The previous prime is 21663451487. The next prime is 21663451561. The reversal of 21663451550 is 5515436612.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 233534 + ... + 312833.

It is an arithmetic number, because the mean of its divisors is an integer number (918854384).

Almost surely, 2^21663451550 is an apocalyptic number.

21663451550 is an abundant number, since it is smaller than the sum of its proper divisors (22441558882).

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

21663451550 is a wasteful number, since it uses less digits than its factorization.

21663451550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 546453 (or 546448 counting only the distinct ones).

The product of its (nonzero) digits is 108000, while the sum is 38.

The spelling of 21663451550 in words is "twenty-one billion, six hundred sixty-three million, four hundred fifty-one thousand, five hundred fifty".