20405750257 has 2 divisors, whose sum is σ = 20405750258. Its totient is φ = 20405750256.

The previous prime is 20405750237. The next prime is 20405750263. The reversal of 20405750257 is 75205750402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19090672561 + 1315077696 = 138169^2 + 36264^2 .

It is a cyclic number.

It is not a de Polignac number, because 20405750257 - 2¹⁹ = 20405225969 is a prime.

It is not a weakly prime, because it can be changed into another prime (20405750237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202875128 + 10202875129.

It is an arithmetic number, because the mean of its divisors is an integer number (10202875129).

Almost surely, 2^20405750257 is an apocalyptic number.

It is an amenable number.

20405750257 is a deficient number, since it is larger than the sum of its proper divisors (1).

20405750257 is an equidigital number, since it uses as much as digits as its factorization.

20405750257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 98000, while the sum is 37.

The spelling of 20405750257 in words is "twenty billion, four hundred five million, seven hundred fifty thousand, two hundred fifty-seven".