20404511125261 has 2 divisors, whose sum is σ = 20404511125262. Its totient is φ = 20404511125260.

The previous prime is 20404511125123. The next prime is 20404511125277. The reversal of 20404511125261 is 16252111540402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17713618650025 + 2690892475236 = 4208755^2 + 1640394^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20404511125261 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20404511125291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202255562630 + 10202255562631.

It is an arithmetic number, because the mean of its divisors is an integer number (10202255562631).

Almost surely, 2^{20404511125261} is an apocalyptic number.

It is an amenable number.

20404511125261 is a deficient number, since it is larger than the sum of its proper divisors (1).

20404511125261 is an equidigital number, since it uses as much as digits as its factorization.

20404511125261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19200, while the sum is 34.

Adding to 20404511125261 its reverse (16252111540402), we get a palindrome (36656622665663).

The spelling of 20404511125261 in words is "twenty trillion, four hundred four billion, five hundred eleven million, one hundred twenty-five thousand, two hundred sixty-one".