21438943 has 8 divisors (see below), whose sum is σ = 21848400. Its totient is φ = 21033408.

The previous prime is 21438931. The next prime is 21438953. The reversal of 21438943 is 34983412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21438943 is a prime.

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

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21438899 and 21438908.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21438913) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11505 + ... + 13237.

It is an arithmetic number, because the mean of its divisors is an integer number (2731050).

Almost surely, 2^21438943 is an apocalyptic number.

21438943 is a deficient number, since it is larger than the sum of its proper divisors (409457).

21438943 is a wasteful number, since it uses less digits than its factorization.

21438943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1961.

The product of its digits is 20736, while the sum is 34.

The square root of 21438943 is about 4630.2206210936. The cubic root of 21438943 is about 277.8014169334.

The spelling of 21438943 in words is "twenty-one million, four hundred thirty-eight thousand, nine hundred forty-three".