20409685 has 12 divisors (see below), whose sum is σ = 24922404. Its totient is φ = 16045440.

The previous prime is 20409679. The next prime is 20409689. The reversal of 20409685 is 58690402.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 10227204 + 10182481 = 3198^2 + 3191^2 .

It is not a de Polignac number, because 20409685 - 2¹¹ = 20407637 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20409685.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20409689) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18057 + ... + 19153.

It is an arithmetic number, because the mean of its divisors is an integer number (2076867).

Almost surely, 2^20409685 is an apocalyptic number.

It is an amenable number.

20409685 is a deficient number, since it is larger than the sum of its proper divisors (4512719).

20409685 is an equidigital number, since it uses as much as digits as its factorization.

20409685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1224 (or 1163 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 20409685 is about 4517.7079365537. The cubic root of 20409685 is about 273.2826753565.

The spelling of 20409685 in words is "twenty million, four hundred nine thousand, six hundred eighty-five".