205991540 has 24 divisors (see below), whose sum is σ = 455350560. Its totient is φ = 78059808.

The previous prime is 205991509. The next prime is 205991581. The reversal of 205991540 is 45199502.

205991540 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 205991540.

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, 270662 + ... + 271421.

It is an arithmetic number, because the mean of its divisors is an integer number (18972940).

Almost surely, 2^205991540 is an apocalyptic number.

205991540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

205991540 is an abundant number, since it is smaller than the sum of its proper divisors (249359020).

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

205991540 is a wasteful number, since it uses less digits than its factorization.

205991540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 542111 (or 542109 counting only the distinct ones).

The product of its (nonzero) digits is 16200, while the sum is 35.

The square root of 205991540 is about 14352.4053733163. The cubic root of 205991540 is about 590.5859734205.

The spelling of 205991540 in words is "two hundred five million, nine hundred ninety-one thousand, five hundred forty".