21939538 has 4 divisors (see below), whose sum is σ = 32909310. Its totient is φ = 10969768.

The previous prime is 21939529. The next prime is 21939559. The reversal of 21939538 is 83593912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 19740249 + 2199289 = 4443^2 + 1483^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21939538.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5484883 + ... + 5484886.

Almost surely, 2^21939538 is an apocalyptic number.

21939538 is a deficient number, since it is larger than the sum of its proper divisors (10969772).

21939538 is a wasteful number, since it uses less digits than its factorization.

21939538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10969771.

The product of its digits is 58320, while the sum is 40.

The square root of 21939538 is about 4683.9660545311. The cubic root of 21939538 is about 279.9470052766.

The spelling of 21939538 in words is "twenty-one million, nine hundred thirty-nine thousand, five hundred thirty-eight".