20505157 has 2 divisors, whose sum is σ = 20505158. Its totient is φ = 20505156.

The previous prime is 20505151. The next prime is 20505169. The reversal of 20505157 is 75150502.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19368801 + 1136356 = 4401^2 + 1066^2 .

It is a cyclic number.

It is not a de Polignac number, because 20505157 - 2¹⁹ = 19980869 is a prime.

It is a super-2 number, since 2×20505157² = 840922927189298, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20505151) 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 as a sum of consecutive naturals, namely, 10252578 + 10252579.

It is an arithmetic number, because the mean of its divisors is an integer number (10252579).

Almost surely, 2^20505157 is an apocalyptic number.

It is an amenable number.

20505157 is a deficient number, since it is larger than the sum of its proper divisors (1).

20505157 is an equidigital number, since it uses as much as digits as its factorization.

20505157 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1750, while the sum is 25.

The square root of 20505157 is about 4528.2620286375. The cubic root of 20505157 is about 273.7081313197.

Adding to 20505157 its reverse (75150502), we get a palindrome (95655659).

The spelling of 20505157 in words is "twenty million, five hundred five thousand, one hundred fifty-seven".