205397794561 has 4 divisors (see below), whose sum is σ = 205410992724. Its totient is φ = 205384596400.

The previous prime is 205397794549. The next prime is 205397794577. The reversal of 205397794561 is 165497793502.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 126624952336 + 78772842225 = 355844^2 + 280665^2 .

It is a cyclic number.

It is not a de Polignac number, because 205397794561 - 2²³ = 205389405953 is a prime.

It is a super-2 number, since 2×205397794561² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 205397794496 and 205397794505.

It is not an unprimeable number, because it can be changed into a prime (205397794061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6575710 + ... + 6606871.

It is an arithmetic number, because the mean of its divisors is an integer number (51352748181).

Almost surely, 2^205397794561 is an apocalyptic number.

It is an amenable number.

205397794561 is a deficient number, since it is larger than the sum of its proper divisors (13198163).

205397794561 is a wasteful number, since it uses less digits than its factorization.

205397794561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13198162.

The product of its (nonzero) digits is 14288400, while the sum is 58.

The spelling of 205397794561 in words is "two hundred five billion, three hundred ninety-seven million, seven hundred ninety-four thousand, five hundred sixty-one".