21542042 has 8 divisors (see below), whose sum is σ = 32397300. Its totient is φ = 10742944.

The previous prime is 21541979. The next prime is 21542063. The reversal of 21542042 is 24024512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 18412681 + 3129361 = 4291^2 + 1769^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13067 + ... + 14622.

Almost surely, 2^21542042 is an apocalyptic number.

21542042 is a deficient number, since it is larger than the sum of its proper divisors (10855258).

21542042 is a wasteful number, since it uses less digits than its factorization.

21542042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28080.

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 21542042 is about 4641.3405391115. The cubic root of 21542042 is about 278.2460168894.

Adding to 21542042 its reverse (24024512), we get a palindrome (45566554).

The spelling of 21542042 in words is "twenty-one million, five hundred forty-two thousand, forty-two".