21038381 has 16 divisors (see below), whose sum is σ = 26256384. Its totient is φ = 16412544.

The previous prime is 21038363. The next prime is 21038389. The reversal of 21038381 is 18383012.

It is a cyclic number.

It is not a de Polignac number, because 21038381 - 2¹⁴ = 21021997 is a prime.

It is a super-2 number, since 2×21038381² = 885226950202322, which contains 22 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21038381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21038389) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5060 + ... + 8226.

It is an arithmetic number, because the mean of its divisors is an integer number (1641024).

Almost surely, 2^21038381 is an apocalyptic number.

It is an amenable number.

21038381 is a deficient number, since it is larger than the sum of its proper divisors (5218003).

21038381 is a wasteful number, since it uses less digits than its factorization.

21038381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3260.

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21038381 is about 4586.7614936903. The cubic root of 21038381 is about 276.0603951358.

The spelling of 21038381 in words is "twenty-one million, thirty-eight thousand, three hundred eighty-one".