21029387 has 2 divisors, whose sum is σ = 21029388. Its totient is φ = 21029386.

The previous prime is 21029369. The next prime is 21029389. The reversal of 21029387 is 78392012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21029387 - 2⁸ = 21029131 is a prime.

Together with 21029389, 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 (21029389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10514693 + 10514694.

It is an arithmetic number, because the mean of its divisors is an integer number (10514694).

Almost surely, 2^21029387 is an apocalyptic number.

21029387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21029387 is an equidigital number, since it uses as much as digits as its factorization.

21029387 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 21029387 is about 4585.7809585718. The cubic root of 21029387 is about 276.0210505193.

The spelling of 21029387 in words is "twenty-one million, twenty-nine thousand, three hundred eighty-seven".