21164618 has 4 divisors (see below), whose sum is σ = 31746930. Its totient is φ = 10582308.

The previous prime is 21164593. The next prime is 21164659. The reversal of 21164618 is 81646112.

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., 20367169 + 797449 = 4513^2 + 893^2 .

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5291153 + ... + 5291156.

Almost surely, 2^21164618 is an apocalyptic number.

21164618 is a deficient number, since it is larger than the sum of its proper divisors (10582312).

21164618 is a wasteful number, since it uses less digits than its factorization.

21164618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10582311.

The product of its digits is 2304, while the sum is 29.

The square root of 21164618 is about 4600.5019291377. The cubic root of 21164618 is about 276.6114446002.

The spelling of 21164618 in words is "twenty-one million, one hundred sixty-four thousand, six hundred eighteen".