21024389 has 2 divisors, whose sum is σ = 21024390. Its totient is φ = 21024388.

The previous prime is 21024379. The next prime is 21024403. The reversal of 21024389 is 98342012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19624900 + 1399489 = 4430^2 + 1183^2 .

It is a cyclic number.

It is not a de Polignac number, because 21024389 - 2⁴ = 21024373 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21024379) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10512194 + 10512195.

It is an arithmetic number, because the mean of its divisors is an integer number (10512195).

Almost surely, 2^21024389 is an apocalyptic number.

It is an amenable number.

21024389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21024389 is an equidigital number, since it uses as much as digits as its factorization.

21024389 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 21024389 is about 4585.2359808411. The cubic root of 21024389 is about 275.9991817171. Note that the first 3 decimals are identical.

The spelling of 21024389 in words is "twenty-one million, twenty-four thousand, three hundred eighty-nine".