21749318 has 4 divisors (see below), whose sum is σ = 32623980. Its totient is φ = 10874658.

The previous prime is 21749317. The next prime is 21749323. The reversal of 21749318 is 81394712.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21749317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5437328 + ... + 5437331.

It is an arithmetic number, because the mean of its divisors is an integer number (8155995).

Almost surely, 2^21749318 is an apocalyptic number.

21749318 is a deficient number, since it is larger than the sum of its proper divisors (10874662).

21749318 is a wasteful number, since it uses less digits than its factorization.

21749318 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10874661.

The product of its digits is 12096, while the sum is 35.

The square root of 21749318 is about 4663.6164078963. The cubic root of 21749318 is about 279.1355909668.

The spelling of 21749318 in words is "twenty-one million, seven hundred forty-nine thousand, three hundred eighteen".