205821810420 has 24 divisors (see below), whose sum is σ = 576301069344. Its totient is φ = 54885816096.

The previous prime is 205821810391. The next prime is 205821810449. The reversal of 205821810420 is 24018128502.

It is an interprime number because it is at equal distance from previous prime (205821810391) and next prime (205821810449).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1715181694 + ... + 1715181813.

It is an arithmetic number, because the mean of its divisors is an integer number (24012544556).

Almost surely, 2^205821810420 is an apocalyptic number.

205821810420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

205821810420 is an abundant number, since it is smaller than the sum of its proper divisors (370479258924).

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

205821810420 is a wasteful number, since it uses less digits than its factorization.

205821810420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3430363519 (or 3430363517 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 33.

Adding to 205821810420 its reverse (24018128502), we get a palindrome (229839938922).

The spelling of 205821810420 in words is "two hundred five billion, eight hundred twenty-one million, eight hundred ten thousand, four hundred twenty".