21345187 has 2 divisors, whose sum is σ = 21345188. Its totient is φ = 21345186.

The previous prime is 21345119. The next prime is 21345211. The reversal of 21345187 is 78154312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21345187 - 2¹¹ = 21343139 is a prime.

It is not a weakly prime, because it can be changed into another prime (21345287) 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 as a sum of consecutive naturals, namely, 10672593 + 10672594.

It is an arithmetic number, because the mean of its divisors is an integer number (10672594).

Almost surely, 2^21345187 is an apocalyptic number.

21345187 is a deficient number, since it is larger than the sum of its proper divisors (1).

21345187 is an equidigital number, since it uses as much as digits as its factorization.

21345187 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6720, while the sum is 31.

The square root of 21345187 is about 4620.0851723751. The cubic root of 21345187 is about 277.3958681881.

Adding to 21345187 its reverse (78154312), we get a palindrome (99499499).

The spelling of 21345187 in words is "twenty-one million, three hundred forty-five thousand, one hundred eighty-seven".