20405665 has 8 divisors (see below), whose sum is σ = 27984960. Its totient is φ = 13992432.

The previous prime is 20405663. The next prime is 20405683. The reversal of 20405665 is 56650402.

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 20405665 - 2¹ = 20405663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20405663) 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, 291475 + ... + 291544.

It is an arithmetic number, because the mean of its divisors is an integer number (3498120).

Almost surely, 2^20405665 is an apocalyptic number.

It is an amenable number.

20405665 is a deficient number, since it is larger than the sum of its proper divisors (7579295).

20405665 is an equidigital number, since it uses as much as digits as its factorization.

20405665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 583031.

The product of its (nonzero) digits is 7200, while the sum is 28.

The square root of 20405665 is about 4517.2629987637. The cubic root of 20405665 is about 273.2647317757.

The spelling of 20405665 in words is "twenty million, four hundred five thousand, six hundred sixty-five".