21043538 has 8 divisors (see below), whose sum is σ = 31844988. Its totient is φ = 10428544.

The previous prime is 21043523. The next prime is 21043543. The reversal of 21043538 is 83534012.

It can be written as a sum of positive squares in 2 ways, for example, as 18344089 + 2699449 = 4283^2 + 1643^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46331 + ... + 46782.

Almost surely, 2^21043538 is an apocalyptic number.

21043538 is a deficient number, since it is larger than the sum of its proper divisors (10801450).

21043538 is a wasteful number, since it uses less digits than its factorization.

21043538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93228.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 21043538 is about 4587.3236205875. The cubic root of 21043538 is about 276.0829495828.

The spelling of 21043538 in words is "twenty-one million, forty-three thousand, five hundred thirty-eight".