20605745 has 4 divisors (see below), whose sum is σ = 24726900. Its totient is φ = 16484592.

The previous prime is 20605733. The next prime is 20605757. The reversal of 20605745 is 54750602.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (20605733) and next prime (20605757).

It can be written as a sum of positive squares in 2 ways, for example, as 13630864 + 6974881 = 3692^2 + 2641^2 .

It is a cyclic number.

It is not a de Polignac number, because 20605745 - 2¹⁶ = 20540209 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2060570 + ... + 2060579.

It is an arithmetic number, because the mean of its divisors is an integer number (6181725).

Almost surely, 2^20605745 is an apocalyptic number.

It is an amenable number.

20605745 is a deficient number, since it is larger than the sum of its proper divisors (4121155).

20605745 is an equidigital number, since it uses as much as digits as its factorization.

20605745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4121154.

The product of its (nonzero) digits is 8400, while the sum is 29.

The square root of 20605745 is about 4539.3551304122. The cubic root of 20605745 is about 274.1549596764.

The spelling of 20605745 in words is "twenty million, six hundred five thousand, seven hundred forty-five".