21164018 has 6 divisors (see below), whose sum is σ = 31755789. Its totient is φ = 10578756.

The previous prime is 21163999. The next prime is 21164029. The reversal of 21164018 is 81046112.

It can be written as a sum of positive squares in 2 ways, for example, as 12061729 + 9102289 = 3473^2 + 3017^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=3253.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21163984 and 21164002.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4880 + ... + 8132.

Almost surely, 2^21164018 is an apocalyptic number.

21164018 is a deficient number, since it is larger than the sum of its proper divisors (10591771).

21164018 is an frugal number, since it uses more digits than its factorization.

21164018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6508 (or 3255 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 21164018 is about 4600.4367183997. The cubic root of 21164018 is about 276.6088306711.

The spelling of 21164018 in words is "twenty-one million, one hundred sixty-four thousand, eighteen".