21361616 has 20 divisors (see below), whose sum is σ = 41580672. Its totient is φ = 10631136.

The previous prime is 21361609. The next prime is 21361619. The reversal of 21361616 is 61616312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21361619) 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 3 ways as a sum of consecutive naturals, for example, 575 + ... + 6561.

Almost surely, 2^21361616 is an apocalyptic number.

It is an amenable number.

21361616 is a deficient number, since it is larger than the sum of its proper divisors (20219056).

21361616 is a wasteful number, since it uses less digits than its factorization.

21361616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6218 (or 6212 counting only the distinct ones).

The product of its digits is 1296, while the sum is 26.

The square root of 21361616 is about 4621.8628279082. The cubic root of 21361616 is about 277.4670187787.

Adding to 21361616 its reverse (61616312), we get a palindrome (82977928).

The spelling of 21361616 in words is "twenty-one million, three hundred sixty-one thousand, six hundred sixteen".