21316635 has 16 divisors (see below), whose sum is σ = 37896480. Its totient is φ = 11368800.

The previous prime is 21316619. The next prime is 21316639. The reversal of 21316635 is 53661312.

21316635 is a `hidden beast` number, since 2 + 13 + 16 + 635 = 666.

It is not a de Polignac number, because 21316635 - 2⁴ = 21316619 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21316599 and 21316608.

It is not an unprimeable number, because it can be changed into a prime (21316639) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78816 + ... + 79085.

It is an arithmetic number, because the mean of its divisors is an integer number (2368530).

Almost surely, 2^21316635 is an apocalyptic number.

21316635 is a deficient number, since it is larger than the sum of its proper divisors (16579845).

21316635 is a wasteful number, since it uses less digits than its factorization.

21316635 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157915 (or 157909 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 21316635 is about 4616.9941520431. The cubic root of 21316635 is about 277.2721284914.

Adding to 21316635 its reverse (53661312), we get a palindrome (74977947).

The spelling of 21316635 in words is "twenty-one million, three hundred sixteen thousand, six hundred thirty-five".