20406665 has 8 divisors (see below), whose sum is σ = 25776960. Its totient is φ = 15466032.

The previous prime is 20406641. The next prime is 20406667. The reversal of 20406665 is 56660402.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20406665 - 2¹⁰ = 20405641 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20406667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 107309 + ... + 107498.

It is an arithmetic number, because the mean of its divisors is an integer number (3222120).

Almost surely, 2^20406665 is an apocalyptic number.

It is an amenable number.

20406665 is a deficient number, since it is larger than the sum of its proper divisors (5370295).

20406665 is a wasteful number, since it uses less digits than its factorization.

20406665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214831.

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 20406665 is about 4517.3736839009. The cubic root of 20406665 is about 273.2691955732.

The spelling of 20406665 in words is "twenty million, four hundred six thousand, six hundred sixty-five".