20505123 has 16 divisors (see below), whose sum is σ = 31977600. Its totient is φ = 12950280.

The previous prime is 20505103. The next prime is 20505127. The reversal of 20505123 is 32150502.

It is a happy number.

It is not a de Polignac number, because 20505123 - 2⁵ = 20505091 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20505096 and 20505105.

It is not an unprimeable number, because it can be changed into a prime (20505127) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 19473 + ... + 20498.

It is an arithmetic number, because the mean of its divisors is an integer number (1998600).

Almost surely, 2^20505123 is an apocalyptic number.

20505123 is a deficient number, since it is larger than the sum of its proper divisors (11472477).

20505123 is a wasteful number, since it uses less digits than its factorization.

20505123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39999 (or 39993 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 20505123 is about 4528.2582744362. The cubic root of 20505123 is about 273.7079800394.

Adding to 20505123 its reverse (32150502), we get a palindrome (52655625).

The spelling of 20505123 in words is "twenty million, five hundred five thousand, one hundred twenty-three".