21038389 has 2 divisors, whose sum is σ = 21038390. Its totient is φ = 21038388.

The previous prime is 21038363. The next prime is 21038393. The reversal of 21038389 is 98383012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15539364 + 5499025 = 3942^2 + 2345^2 .

It is a cyclic number.

It is not a de Polignac number, because 21038389 - 2¹¹ = 21036341 is a prime.

It is a super-2 number, since 2×21038389² = 885227623430642, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21038789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10519194 + 10519195.

It is an arithmetic number, because the mean of its divisors is an integer number (10519195).

Almost surely, 2^21038389 is an apocalyptic number.

It is an amenable number.

21038389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21038389 is an equidigital number, since it uses as much as digits as its factorization.

21038389 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 21038389 is about 4586.7623657652. The cubic root of 21038389 is about 276.0604301271.

The spelling of 21038389 in words is "twenty-one million, thirty-eight thousand, three hundred eighty-nine".