21326618 has 4 divisors (see below), whose sum is σ = 31989930. Its totient is φ = 10663308.

The previous prime is 21326609. The next prime is 21326621. The reversal of 21326618 is 81662312.

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., 18344089 + 2982529 = 4283^2 + 1727^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5331653 + ... + 5331656.

Almost surely, 2^21326618 is an apocalyptic number.

21326618 is a deficient number, since it is larger than the sum of its proper divisors (10663312).

21326618 is a wasteful number, since it uses less digits than its factorization.

21326618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10663311.

The product of its digits is 3456, while the sum is 29.

The square root of 21326618 is about 4618.0751401423. The cubic root of 21326618 is about 277.3154057358.

The spelling of 21326618 in words is "twenty-one million, three hundred twenty-six thousand, six hundred eighteen".