21812242 has 4 divisors (see below), whose sum is σ = 32718366. Its totient is φ = 10906120.

The previous prime is 21812239. The next prime is 21812249. The reversal of 21812242 is 24221812.

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., 15202201 + 6610041 = 3899^2 + 2571^2 .

It is a Smith number, since the sum of its digits (22) 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 (21812249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5453059 + ... + 5453062.

Almost surely, 2^21812242 is an apocalyptic number.

21812242 is a deficient number, since it is larger than the sum of its proper divisors (10906124).

21812242 is a wasteful number, since it uses less digits than its factorization.

21812242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10906123.

The product of its digits is 512, while the sum is 22.

The square root of 21812242 is about 4670.3578021389. The cubic root of 21812242 is about 279.4045253209.

The spelling of 21812242 in words is "twenty-one million, eight hundred twelve thousand, two hundred forty-two".