20045917 has 4 divisors (see below), whose sum is σ = 20173756. Its totient is φ = 19918080.

The previous prime is 20045887. The next prime is 20045929. The reversal of 20045917 is 71954002.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 71954002 = 2 ⋅35977001.

It can be written as a sum of positive squares in 2 ways, for example, as 6584356 + 13461561 = 2566^2 + 3669^2 .

It is a cyclic number.

It is not a de Polignac number, because 20045917 - 2⁷ = 20045789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20045957) 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, 63684 + ... + 63997.

It is an arithmetic number, because the mean of its divisors is an integer number (5043439).

Almost surely, 2^20045917 is an apocalyptic number.

It is an amenable number.

20045917 is a deficient number, since it is larger than the sum of its proper divisors (127839).

20045917 is a wasteful number, since it uses less digits than its factorization.

20045917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127838.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 20045917 is about 4477.2666885054. The cubic root of 20045917 is about 271.6493327459.

Adding to 20045917 its reverse (71954002), we get a palindrome (91999919).

It can be divided in two parts, 2004 and 5917, that added together give a square (7921 = 89²).

The spelling of 20045917 in words is "twenty million, forty-five thousand, nine hundred seventeen".