205811866428 has 168 divisors, whose sum is σ = 568224214992. Its totient is φ = 57968822016.

The previous prime is 205811866423. The next prime is 205811866433. The reversal of 205811866428 is 824668118502.

It is an interprime number because it is at equal distance from previous prime (205811866423) and next prime (205811866433).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205811866423) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 103059526 + ... + 103061522.

It is an arithmetic number, because the mean of its divisors is an integer number (3382286994).

Almost surely, 2^205811866428 is an apocalyptic number.

205811866428 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 205811866428, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (284112107496).

205811866428 is an abundant number, since it is smaller than the sum of its proper divisors (362412348564).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

205811866428 is an frugal number, since it uses more digits than its factorization.

205811866428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2119 (or 2082 counting only the distinct ones).

The product of its (nonzero) digits is 1474560, while the sum is 51.

The spelling of 205811866428 in words is "two hundred five billion, eight hundred eleven million, eight hundred sixty-six thousand, four hundred twenty-eight".