20939645 has 4 divisors (see below), whose sum is σ = 25127580. Its totient is φ = 16751712.

The previous prime is 20939641. The next prime is 20939647. The reversal of 20939645 is 54693902.

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 9897316 + 11042329 = 3146^2 + 3323^2 .

It is a cyclic number.

It is not a de Polignac number, because 20939645 - 2² = 20939641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20939599 and 20939608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20939641) 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, 2093960 + ... + 2093969.

It is an arithmetic number, because the mean of its divisors is an integer number (6281895).

Almost surely, 2^20939645 is an apocalyptic number.

It is an amenable number.

20939645 is a deficient number, since it is larger than the sum of its proper divisors (4187935).

20939645 is an equidigital number, since it uses as much as digits as its factorization.

20939645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4187934.

The product of its (nonzero) digits is 58320, while the sum is 38.

The square root of 20939645 is about 4575.9856861664. The cubic root of 20939645 is about 275.6278547052.

The spelling of 20939645 in words is "twenty million, nine hundred thirty-nine thousand, six hundred forty-five".