21543938 has 16 divisors (see below), whose sum is σ = 34957440. Its totient is φ = 9898896.

The previous prime is 21543931. The next prime is 21543961. The reversal of 21543938 is 83934512.

It is a junction number, because it is equal to n+sod(n) for n = 21543898 and 21543907.

It is not an unprimeable number, because it can be changed into a prime (21543931) 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, 4481 + ... + 7947.

It is an arithmetic number, because the mean of its divisors is an integer number (2184840).

Almost surely, 2^21543938 is an apocalyptic number.

21543938 is a deficient number, since it is larger than the sum of its proper divisors (13413502).

21543938 is a wasteful number, since it uses less digits than its factorization.

21543938 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3721.

The product of its digits is 25920, while the sum is 35.

The square root of 21543938 is about 4641.5447859522. The cubic root of 21543938 is about 278.2541798260.

The spelling of 21543938 in words is "twenty-one million, five hundred forty-three thousand, nine hundred thirty-eight".