21616155 has 24 divisors (see below), whose sum is σ = 40875120. Its totient is φ = 10480320.

The previous prime is 21616141. The next prime is 21616157. The reversal of 21616155 is 55161612.

21616155 = 606² + 607² + ... + 659².

It is a happy number.

It is not a de Polignac number, because 21616155 - 2⁴ = 21616139 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21616157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21340 + ... + 22329.

It is an arithmetic number, because the mean of its divisors is an integer number (1703130).

Almost surely, 2^21616155 is an apocalyptic number.

21616155 is a deficient number, since it is larger than the sum of its proper divisors (19258965).

21616155 is a wasteful number, since it uses less digits than its factorization.

21616155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43691 (or 43688 counting only the distinct ones).

The product of its digits is 1800, while the sum is 27.

The square root of 21616155 is about 4649.3176918769. The cubic root of 21616155 is about 278.5647431475.

Adding to 21616155 its reverse (55161612), we get a palindrome (76777767).

The spelling of 21616155 in words is "twenty-one million, six hundred sixteen thousand, one hundred fifty-five".