20918669 has 4 divisors (see below), whose sum is σ = 21261660. Its totient is φ = 20575680.

The previous prime is 20918629. The next prime is 20918699. The reversal of 20918669 is 96681902.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8773444 + 12145225 = 2962^2 + 3485^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20918669 is a prime.

It is a super-2 number, since 2×20918669² = 875181425463122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20918629) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 171404 + ... + 171525.

It is an arithmetic number, because the mean of its divisors is an integer number (5315415).

Almost surely, 2^20918669 is an apocalyptic number.

It is an amenable number.

20918669 is a deficient number, since it is larger than the sum of its proper divisors (342991).

20918669 is an equidigital number, since it uses as much as digits as its factorization.

20918669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 342990.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 20918669 is about 4573.6931466814. The cubic root of 20918669 is about 275.5357884915.

It can be divided in two parts, 209 and 18669, that multiplied together give a triangular number (3901821 = T₂₇₉₃).

The spelling of 20918669 in words is "twenty million, nine hundred eighteen thousand, six hundred sixty-nine".