20405129 has 2 divisors, whose sum is σ = 20405130. Its totient is φ = 20405128.

The previous prime is 20405123. The next prime is 20405137. The reversal of 20405129 is 92150402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18079504 + 2325625 = 4252^2 + 1525^2 .

It is a cyclic number.

It is not a de Polignac number, because 20405129 - 2⁴ = 20405113 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20405123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202564 + 10202565.

It is an arithmetic number, because the mean of its divisors is an integer number (10202565).

Almost surely, 2^20405129 is an apocalyptic number.

It is an amenable number.

20405129 is a deficient number, since it is larger than the sum of its proper divisors (1).

20405129 is an equidigital number, since it uses as much as digits as its factorization.

20405129 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 20405129 is about 4517.2036704138. The cubic root of 20405129 is about 273.2623391203.

The spelling of 20405129 in words is "twenty million, four hundred five thousand, one hundred twenty-nine".