21605116 has 24 divisors (see below), whose sum is σ = 42124320. Its totient is φ = 9627072.

The previous prime is 21605107. The next prime is 21605117. The reversal of 21605116 is 61150612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21605117) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5656 + ... + 8671.

It is an arithmetic number, because the mean of its divisors is an integer number (1755180).

Almost surely, 2^21605116 is an apocalyptic number.

21605116 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21605116 is a deficient number, since it is larger than the sum of its proper divisors (20519204).

21605116 is a wasteful number, since it uses less digits than its factorization.

21605116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14373 (or 14371 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21605116 is about 4648.1303768289. The cubic root of 21605116 is about 278.5173156593.

Adding to 21605116 its reverse (61150612), we get a palindrome (82755728).

The spelling of 21605116 in words is "twenty-one million, six hundred five thousand, one hundred sixteen".