20809601 has 4 divisors (see below), whose sum is σ = 21150804. Its totient is φ = 20468400.

The previous prime is 20809583. The next prime is 20809619. The reversal of 20809601 is 10690802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10690802 = 2 ⋅5345401.

It is an interprime number because it is at equal distance from previous prime (20809583) and next prime (20809619).

It can be written as a sum of positive squares in 2 ways, for example, as 5755201 + 15054400 = 2399^2 + 3880^2 .

It is a cyclic number.

It is not a de Polignac number, because 20809601 - 2²² = 16615297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20809631) 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, 170510 + ... + 170631.

It is an arithmetic number, because the mean of its divisors is an integer number (5287701).

Almost surely, 2^20809601 is an apocalyptic number.

It is an amenable number.

20809601 is a deficient number, since it is larger than the sum of its proper divisors (341203).

20809601 is an equidigital number, since it uses as much as digits as its factorization.

20809601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341202.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 20809601 is about 4561.7541582159. The cubic root of 20809601 is about 275.0560811245.

The spelling of 20809601 in words is "twenty million, eight hundred nine thousand, six hundred one".