21939938 has 4 divisors (see below), whose sum is σ = 32909910. Its totient is φ = 10969968.

The previous prime is 21939937. The next prime is 21939977. The reversal of 21939938 is 83993912.

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., 11135569 + 10804369 = 3337^2 + 3287^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21939937) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5484983 + ... + 5484986.

Almost surely, 2^21939938 is an apocalyptic number.

21939938 is a deficient number, since it is larger than the sum of its proper divisors (10969972).

21939938 is a wasteful number, since it uses less digits than its factorization.

21939938 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10969971.

The product of its digits is 104976, while the sum is 44.

The square root of 21939938 is about 4684.0087531942. The cubic root of 21939938 is about 279.9487065905.

The spelling of 21939938 in words is "twenty-one million, nine hundred thirty-nine thousand, nine hundred thirty-eight".