21938242 has 4 divisors (see below), whose sum is σ = 32907366. Its totient is φ = 10969120.

The previous prime is 21938207. The next prime is 21938243. The reversal of 21938242 is 24283912.

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., 11498881 + 10439361 = 3391^2 + 3231^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21938243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5484559 + ... + 5484562.

Almost surely, 2^21938242 is an apocalyptic number.

21938242 is a deficient number, since it is larger than the sum of its proper divisors (10969124).

21938242 is a wasteful number, since it uses less digits than its factorization.

21938242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10969123.

The product of its digits is 6912, while the sum is 31.

The square root of 21938242 is about 4683.8277081891. The cubic root of 21938242 is about 279.9414928776.

The spelling of 21938242 in words is "twenty-one million, nine hundred thirty-eight thousand, two hundred forty-two".