21117550 has 24 divisors (see below), whose sum is σ = 41347800. Its totient is φ = 8002080.

The previous prime is 21117521. The next prime is 21117557. The reversal of 21117550 is 5571112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21117557) 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, 10165 + ... + 12064.

It is an arithmetic number, because the mean of its divisors is an integer number (1722825).

Almost surely, 2^21117550 is an apocalyptic number.

21117550 is a deficient number, since it is larger than the sum of its proper divisors (20230250).

21117550 is a wasteful number, since it uses less digits than its factorization.

21117550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22260 (or 22255 counting only the distinct ones).

The product of its (nonzero) digits is 350, while the sum is 22.

The square root of 21117550 is about 4595.3835530889. The cubic root of 21117550 is about 276.4062403168.

Adding to 21117550 its reverse (5571112), we get a palindrome (26688662).

The spelling of 21117550 in words is "twenty-one million, one hundred seventeen thousand, five hundred fifty".