21323550 has 24 divisors (see below), whose sum is σ = 52882776. Its totient is φ = 5686240.

The previous prime is 21323531. The next prime is 21323591. The reversal of 21323550 is 5532312.

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, 70929 + ... + 71228.

It is an arithmetic number, because the mean of its divisors is an integer number (2203449).

Almost surely, 2^21323550 is an apocalyptic number.

21323550 is an abundant number, since it is smaller than the sum of its proper divisors (31559226).

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

21323550 is a wasteful number, since it uses less digits than its factorization.

21323550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142172 (or 142167 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 21.

The square root of 21323550 is about 4617.7429551676. The cubic root of 21323550 is about 277.3021071048.

Adding to 21323550 its reverse (5532312), we get a palindrome (26855862).

The spelling of 21323550 in words is "twenty-one million, three hundred twenty-three thousand, five hundred fifty".