205680390400 has 81 divisors (see below), whose sum is σ = 509180922271. Its totient is φ = 82257643520.

The previous prime is 205680390389. The next prime is 205680390403. The reversal of 205680390400 is 4093086502.

The square root of 205680390400 is 453520.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 33369059584 + 172311330816 = 182672^2 + 415104^2 .

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 205680390400.

It is not an unprimeable number, because it can be changed into a prime (205680390403) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 36278766 + ... + 36284434.

Almost surely, 2^205680390400 is an apocalyptic number.

205680390400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

205680390400 is the 453520-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 205680390400

205680390400 is an abundant number, since it is smaller than the sum of its proper divisors (303500531871).

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

205680390400 is an frugal number, since it uses more digits than its factorization.

205680390400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11364 (or 5676 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 37.

The spelling of 205680390400 in words is "two hundred five billion, six hundred eighty million, three hundred ninety thousand, four hundred".