205782730031921 has 4 divisors (see below), whose sum is σ = 235180262893632. Its totient is φ = 176385197170212.

The previous prime is 205782730031899. The next prime is 205782730031927. The reversal of 205782730031921 is 129130037287502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-205782730031921 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 205782730031921.

It is not an unprimeable number, because it can be changed into a prime (205782730031927) 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, 14698766430845 + ... + 14698766430858.

It is an arithmetic number, because the mean of its divisors is an integer number (58795065723408).

Almost surely, 2^{205782730031921} is an apocalyptic number.

It is an amenable number.

205782730031921 is a deficient number, since it is larger than the sum of its proper divisors (29397532861711).

205782730031921 is an equidigital number, since it uses as much as digits as its factorization.

205782730031921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29397532861710.

The product of its (nonzero) digits is 1270080, while the sum is 50.

The spelling of 205782730031921 in words is "two hundred five trillion, seven hundred eighty-two billion, seven hundred thirty million, thirty-one thousand, nine hundred twenty-one".