20517123 has 24 divisors (see below), whose sum is σ = 31122000. Its totient is φ = 11999680.

The previous prime is 20517121. The next prime is 20517157. The reversal of 20517123 is 32171502.

It is not a de Polignac number, because 20517123 - 2¹ = 20517121 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20517123.

It is not an unprimeable number, because it can be changed into a prime (20517121) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9553 + ... + 11501.

It is an arithmetic number, because the mean of its divisors is an integer number (1296750).

Almost surely, 2^20517123 is an apocalyptic number.

20517123 is a deficient number, since it is larger than the sum of its proper divisors (10604877).

20517123 is a wasteful number, since it uses less digits than its factorization.

20517123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2003 (or 1992 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 20517123 is about 4529.5830933983. The cubic root of 20517123 is about 273.7613627193.

Adding to 20517123 its reverse (32171502), we get a palindrome (52688625).

The spelling of 20517123 in words is "twenty million, five hundred seventeen thousand, one hundred twenty-three".