21004550 has 24 divisors (see below), whose sum is σ = 44650416. Its totient is φ = 7201440.

The previous prime is 21004549. The next prime is 21004579. The reversal of 21004550 is 5540012.

It is a super-2 number, since 2×21004550² = 882382241405000, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29657 + ... + 30356.

It is an arithmetic number, because the mean of its divisors is an integer number (1860434).

Almost surely, 2^21004550 is an apocalyptic number.

21004550 is an abundant number, since it is smaller than the sum of its proper divisors (23645866).

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

21004550 is a wasteful number, since it uses less digits than its factorization.

21004550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60032 (or 60027 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 21004550 is about 4583.0721137682. The cubic root of 21004550 is about 275.9123417627.

Adding to 21004550 its reverse (5540012), we get a palindrome (26544562).

The spelling of 21004550 in words is "twenty-one million, four thousand, five hundred fifty".