205430255621 has 4 divisors (see below), whose sum is σ = 205841940000. Its totient is φ = 205018571244.

The previous prime is 205430255579. The next prime is 205430255647. The reversal of 205430255621 is 126552034502.

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, and also an emirpimes, since its reverse is a distinct semiprime: 126552034502 = 2 ⋅63276017251.

It is a cyclic number.

It is not a de Polignac number, because 205430255621 - 2⁶ = 205430255557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205430255321) 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, 205841441 + ... + 205842438.

It is an arithmetic number, because the mean of its divisors is an integer number (51460485000).

Almost surely, 2^205430255621 is an apocalyptic number.

It is an amenable number.

205430255621 is a deficient number, since it is larger than the sum of its proper divisors (411684379).

205430255621 is an equidigital number, since it uses as much as digits as its factorization.

205430255621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411684378.

The product of its (nonzero) digits is 72000, while the sum is 35.

The spelling of 205430255621 in words is "two hundred five billion, four hundred thirty million, two hundred fifty-five thousand, six hundred twenty-one".