20407661 has 4 divisors (see below), whose sum is σ = 20687292. Its totient is φ = 20128032.

The previous prime is 20407643. The next prime is 20407669. The reversal of 20407661 is 16670402.

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 7946761 + 12460900 = 2819^2 + 3530^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20407661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20407661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20407669) 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, 139706 + ... + 139851.

It is an arithmetic number, because the mean of its divisors is an integer number (5171823).

Almost surely, 2^20407661 is an apocalyptic number.

It is an amenable number.

20407661 is a deficient number, since it is larger than the sum of its proper divisors (279631).

20407661 is an equidigital number, since it uses as much as digits as its factorization.

20407661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 279630.

The product of its (nonzero) digits is 2016, while the sum is 26.

The square root of 20407661 is about 4517.4839236017. The cubic root of 20407661 is about 273.2736413706.

The spelling of 20407661 in words is "twenty million, four hundred seven thousand, six hundred sixty-one".