21938542 has 4 divisors (see below), whose sum is σ = 32907816. Its totient is φ = 10969270.

The previous prime is 21938533. The next prime is 21938549. The reversal of 21938542 is 24583912.

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

It is a junction number, because it is equal to n+sod(n) for n = 21938498 and 21938507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21938549) 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, 5484634 + ... + 5484637.

It is an arithmetic number, because the mean of its divisors is an integer number (8226954).

Almost surely, 2^21938542 is an apocalyptic number.

21938542 is a deficient number, since it is larger than the sum of its proper divisors (10969274).

21938542 is a wasteful number, since it uses less digits than its factorization.

21938542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10969273.

The product of its digits is 17280, while the sum is 34.

The square root of 21938542 is about 4683.8597331688. The cubic root of 21938542 is about 279.9427689152.

The spelling of 21938542 in words is "twenty-one million, nine hundred thirty-eight thousand, five hundred forty-two".