21903218 has 4 divisors (see below), whose sum is σ = 32854830. Its totient is φ = 10951608.

The previous prime is 21903197. The next prime is 21903229. The reversal of 21903218 is 81230912.

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., 19333609 + 2569609 = 4397^2 + 1603^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5475803 + ... + 5475806.

Almost surely, 2^21903218 is an apocalyptic number.

21903218 is a deficient number, since it is larger than the sum of its proper divisors (10951612).

21903218 is a wasteful number, since it uses less digits than its factorization.

21903218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10951611.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 21903218 is about 4680.0873923464. The cubic root of 21903218 is about 279.7924397137.

The spelling of 21903218 in words is "twenty-one million, nine hundred three thousand, two hundred eighteen".