21203642 has 8 divisors (see below), whose sum is σ = 32581332. Its totient is φ = 10343200.

The previous prime is 21203621. The next prime is 21203671. The reversal of 21203642 is 24630212.

It can be written as a sum of positive squares in 2 ways, for example, as 17397241 + 3806401 = 4171^2 + 1951^2 .

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

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, 129209 + ... + 129372.

Almost surely, 2^21203642 is an apocalyptic number.

21203642 is a deficient number, since it is larger than the sum of its proper divisors (11377690).

21203642 is a wasteful number, since it uses less digits than its factorization.

21203642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258624.

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 21203642 is about 4604.7412522312. The cubic root of 21203642 is about 276.7813485628.

Adding to 21203642 its reverse (24630212), we get a palindrome (45833854).

The spelling of 21203642 in words is "twenty-one million, two hundred three thousand, six hundred forty-two".