205551155720 has 64 divisors (see below), whose sum is σ = 487169812800. Its totient is φ = 77838969600.

The previous prime is 205551155713. The next prime is 205551155749. The reversal of 205551155720 is 27551155502.

It is a Harshad number since it is a multiple of its sum of digits (38).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1009562 + ... + 1195958.

It is an arithmetic number, because the mean of its divisors is an integer number (7612028325).

Almost surely, 2^205551155720 is an apocalyptic number.

205551155720 is a gapful number since it is divisible by the number (20) 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 205551155720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (243584906400).

205551155720 is an abundant number, since it is smaller than the sum of its proper divisors (281618657080).

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

205551155720 is a wasteful number, since it uses less digits than its factorization.

205551155720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187878 (or 187874 counting only the distinct ones).

The product of its (nonzero) digits is 87500, while the sum is 38.

The spelling of 205551155720 in words is "two hundred five billion, five hundred fifty-one million, one hundred fifty-five thousand, seven hundred twenty".