21288550 has 24 divisors (see below), whose sum is σ = 41682600. Its totient is φ = 8066880.

The previous prime is 21288529. The next prime is 21288551. The reversal of 21288550 is 5588212.

It is a super-2 number, since 2×21288550² = 906404722205000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21288551) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10255 + ... + 12154.

It is an arithmetic number, because the mean of its divisors is an integer number (1736775).

Almost surely, 2^21288550 is an apocalyptic number.

21288550 is a deficient number, since it is larger than the sum of its proper divisors (20394050).

21288550 is a wasteful number, since it uses less digits than its factorization.

21288550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22440 (or 22435 counting only the distinct ones).

The product of its (nonzero) digits is 6400, while the sum is 31.

The square root of 21288550 is about 4613.9516685808. The cubic root of 21288550 is about 277.1503048523.

The spelling of 21288550 in words is "twenty-one million, two hundred eighty-eight thousand, five hundred fifty".