21845550 has 24 divisors (see below), whose sum is σ = 54177336. Its totient is φ = 5825440.

The previous prime is 21845543. The next prime is 21845557. The reversal of 21845550 is 5554812.

21845550 = 417² + 418² + ... + 516².

It is an interprime number because it is at equal distance from previous prime (21845543) and next prime (21845557).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21845557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 72669 + ... + 72968.

It is an arithmetic number, because the mean of its divisors is an integer number (2257389).

Almost surely, 2^21845550 is an apocalyptic number.

21845550 is an abundant number, since it is smaller than the sum of its proper divisors (32331786).

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

21845550 is a wasteful number, since it uses less digits than its factorization.

21845550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145652 (or 145647 counting only the distinct ones).

The product of its (nonzero) digits is 8000, while the sum is 30.

The square root of 21845550 is about 4673.9223356834. The cubic root of 21845550 is about 279.5466729106.

The spelling of 21845550 in words is "twenty-one million, eight hundred forty-five thousand, five hundred fifty".