20517445 has 12 divisors (see below), whose sum is σ = 26661636. Its totient is φ = 15150720.

The previous prime is 20517439. The next prime is 20517451. The reversal of 20517445 is 54471502.

20517445 = 261² + 262² + ... + 429².

It is an interprime number because it is at equal distance from previous prime (20517439) and next prime (20517451).

It can be written as a sum of positive squares in 6 ways, for example, as 599076 + 19918369 = 774^2 + 4463^2 .

It is not a de Polignac number, because 20517445 - 2¹⁹ = 19993157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11296 + ... + 12985.

It is an arithmetic number, because the mean of its divisors is an integer number (2221803).

Almost surely, 2^20517445 is an apocalyptic number.

It is an amenable number.

20517445 is a deficient number, since it is larger than the sum of its proper divisors (6144191).

20517445 is a wasteful number, since it uses less digits than its factorization.

20517445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24312 (or 24299 counting only the distinct ones).

The product of its (nonzero) digits is 5600, while the sum is 28.

The square root of 20517445 is about 4529.6186373689. The cubic root of 20517445 is about 273.7627948677.

Adding to 20517445 its reverse (54471502), we get a palindrome (74988947).

The spelling of 20517445 in words is "twenty million, five hundred seventeen thousand, four hundred forty-five".