21203018 has 4 divisors (see below), whose sum is σ = 31804530. Its totient is φ = 10601508.

The previous prime is 21203011. The next prime is 21203023. The reversal of 21203018 is 81030212.

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., 16216729 + 4986289 = 4027^2 + 2233^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21202987 and 21203005.

It is not an unprimeable number, because it can be changed into a prime (21203011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5300753 + ... + 5300756.

Almost surely, 2^21203018 is an apocalyptic number.

21203018 is a deficient number, since it is larger than the sum of its proper divisors (10601512).

21203018 is a wasteful number, since it uses less digits than its factorization.

21203018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10601511.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21203018 is about 4604.6734954826. The cubic root of 21203018 is about 276.7786334120.

The spelling of 21203018 in words is "twenty-one million, two hundred three thousand, eighteen".