205421400557 has 2 divisors, whose sum is σ = 205421400558. Its totient is φ = 205421400556.

The previous prime is 205421400529. The next prime is 205421400563. The reversal of 205421400557 is 755004124502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 180751672201 + 24669728356 = 425149^2 + 157066^2 .

It is a cyclic number.

It is not a de Polignac number, because 205421400557 - 2¹² = 205421396461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205421400757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102710700278 + 102710700279.

It is an arithmetic number, because the mean of its divisors is an integer number (102710700279).

Almost surely, 2^205421400557 is an apocalyptic number.

It is an amenable number.

205421400557 is a deficient number, since it is larger than the sum of its proper divisors (1).

205421400557 is an equidigital number, since it uses as much as digits as its factorization.

205421400557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56000, while the sum is 35.

The spelling of 205421400557 in words is "two hundred five billion, four hundred twenty-one million, four hundred thousand, five hundred fifty-seven".