21302389 has 2 divisors, whose sum is σ = 21302390. Its totient is φ = 21302388.

The previous prime is 21302387. The next prime is 21302399. The reversal of 21302389 is 98320312.

21302389 = T₃₇₆₇ + T₃₇₆₈ + T₃₇₆₉.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20566225 + 736164 = 4535^2 + 858^2 .

It is a cyclic number.

It is not a de Polignac number, because 21302389 - 2¹ = 21302387 is a prime.

Together with 21302387, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21302387) 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, 10651194 + 10651195.

It is an arithmetic number, because the mean of its divisors is an integer number (10651195).

Almost surely, 2^21302389 is an apocalyptic number.

21302389 is the 3769-th centered triangular number.

It is an amenable number.

21302389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21302389 is an equidigital number, since it uses as much as digits as its factorization.

21302389 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 21302389 is about 4615.4511155466. The cubic root of 21302389 is about 277.2103473361.

The spelling of 21302389 in words is "twenty-one million, three hundred two thousand, three hundred eighty-nine".