20201945 has 4 divisors (see below), whose sum is σ = 24242340. Its totient is φ = 16161552.

The previous prime is 20201939. The next prime is 20201969. The reversal of 20201945 is 54910202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54910202 = 2 ⋅27455101.

It can be written as a sum of positive squares in 2 ways, for example, as 16024009 + 4177936 = 4003^2 + 2044^2 .

It is a cyclic number.

It is not a de Polignac number, because 20201945 - 2⁸ = 20201689 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20201945.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2020190 + ... + 2020199.

It is an arithmetic number, because the mean of its divisors is an integer number (6060585).

Almost surely, 2^20201945 is an apocalyptic number.

It is an amenable number.

20201945 is a deficient number, since it is larger than the sum of its proper divisors (4040395).

20201945 is an equidigital number, since it uses as much as digits as its factorization.

20201945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4040394.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 20201945 is about 4494.6573840505. The cubic root of 20201945 is about 272.3523089364.

The spelling of 20201945 in words is "twenty million, two hundred one thousand, nine hundred forty-five".