21616387 has 8 divisors (see below), whose sum is σ = 23661680. Its totient is φ = 19625760.

The previous prime is 21616373. The next prime is 21616417. The reversal of 21616387 is 78361612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21616387 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21616327) 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, 12837 + ... + 14422.

It is an arithmetic number, because the mean of its divisors is an integer number (2957710).

Almost surely, 2^21616387 is an apocalyptic number.

21616387 is a deficient number, since it is larger than the sum of its proper divisors (2045293).

21616387 is a wasteful number, since it uses less digits than its factorization.

21616387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27333.

The product of its digits is 12096, while the sum is 34.

The square root of 21616387 is about 4649.3426417075. The cubic root of 21616387 is about 278.5657397292.

Adding to 21616387 its reverse (78361612), we get a palindrome (99977999).

The spelling of 21616387 in words is "twenty-one million, six hundred sixteen thousand, three hundred eighty-seven".