21242818 has 8 divisors (see below), whose sum is σ = 31941180. Its totient is φ = 10595760.

The previous prime is 21242807. The next prime is 21242821. The reversal of 21242818 is 81824212.

It can be written as a sum of positive squares in 2 ways, for example, as 13860729 + 7382089 = 3723^2 + 2717^2 .

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

It is a super-2 number, since 2×21242818² = 902514633162248, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11773 + ... + 13456.

Almost surely, 2^21242818 is an apocalyptic number.

21242818 is a deficient number, since it is larger than the sum of its proper divisors (10698362).

21242818 is a wasteful number, since it uses less digits than its factorization.

21242818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25652.

The product of its digits is 2048, while the sum is 28.

The square root of 21242818 is about 4608.9931655406. The cubic root of 21242818 is about 276.9517047525.

The spelling of 21242818 in words is "twenty-one million, two hundred forty-two thousand, eight hundred eighteen".