21258242 has 4 divisors (see below), whose sum is σ = 31887366. Its totient is φ = 10629120.

The previous prime is 21258199. The next prime is 21258253. The reversal of 21258242 is 24285212.

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., 10883401 + 10374841 = 3299^2 + 3221^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5314559 + ... + 5314562.

Almost surely, 2^21258242 is an apocalyptic number.

21258242 is a deficient number, since it is larger than the sum of its proper divisors (10629124).

21258242 is a wasteful number, since it uses less digits than its factorization.

21258242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10629123.

The product of its digits is 2560, while the sum is 26.

The square root of 21258242 is about 4610.6661123963. Note that the first 3 decimals coincide. The cubic root of 21258242 is about 277.0187182979.

The spelling of 21258242 in words is "twenty-one million, two hundred fifty-eight thousand, two hundred forty-two".