21302387 has 2 divisors, whose sum is σ = 21302388. Its totient is φ = 21302386.

The previous prime is 21302371. The next prime is 21302389. The reversal of 21302387 is 78320312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21302387 - 2⁴ = 21302371 is a prime.

Together with 21302389, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21302389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651193 + 10651194.

It is an arithmetic number, because the mean of its divisors is an integer number (10651194).

Almost surely, 2^21302387 is an apocalyptic number.

21302387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21302387 is an equidigital number, since it uses as much as digits as its factorization.

21302387 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 26.

The square root of 21302387 is about 4615.4508988830. The cubic root of 21302387 is about 277.2103386607.

Adding to 21302387 its reverse (78320312), we get a palindrome (99622699).

The spelling of 21302387 in words is "twenty-one million, three hundred two thousand, three hundred eighty-seven".