21116387 has 4 divisors (see below), whose sum is σ = 21227136. Its totient is φ = 21005640.

The previous prime is 21116377. The next prime is 21116393. The reversal of 21116387 is 78361112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21116387 - 2¹² = 21112291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21116317) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55088 + ... + 55469.

It is an arithmetic number, because the mean of its divisors is an integer number (5306784).

Almost surely, 2^21116387 is an apocalyptic number.

21116387 is a deficient number, since it is larger than the sum of its proper divisors (110749).

21116387 is a wasteful number, since it uses less digits than its factorization.

21116387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110748.

The product of its digits is 2016, while the sum is 29.

The square root of 21116387 is about 4595.2570113107. The cubic root of 21116387 is about 276.4011660799.

Adding to 21116387 its reverse (78361112), we get a palindrome (99477499).

The spelling of 21116387 in words is "twenty-one million, one hundred sixteen thousand, three hundred eighty-seven".