21050550 has 96 divisors (see below), whose sum is σ = 59996160. Its totient is φ = 5421600.

The previous prime is 21050527. The next prime is 21050567. The reversal of 21050550 is 5505012.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 41599 + ... + 42101.

It is an arithmetic number, because the mean of its divisors is an integer number (624960).

Almost surely, 2^21050550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21050550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29998080).

21050550 is an abundant number, since it is smaller than the sum of its proper divisors (38945610).

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

21050550 is a wasteful number, since it uses less digits than its factorization.

21050550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 555 (or 544 counting only the distinct ones).

The product of its (nonzero) digits is 250, while the sum is 18.

The square root of 21050550 is about 4588.0878369970. The cubic root of 21050550 is about 276.1136110724.

Adding to 21050550 its reverse (5505012), we get a palindrome (26555562).

The spelling of 21050550 in words is "twenty-one million, fifty thousand, five hundred fifty".