115821540 has 36 divisors (see below), whose sum is σ = 351325884. Its totient is φ = 30885696.

The previous prime is 115821533. The next prime is 115821571. The reversal of 115821540 is 45128511.

115821540 is a `hidden beast` number, since 115 + 8 + 2 + 1 + 540 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 27311076 + 88510464 = 5226^2 + 9408^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 321547 + ... + 321906.

Almost surely, 2^115821540 is an apocalyptic number.

115821540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

115821540 is an abundant number, since it is smaller than the sum of its proper divisors (235504344).

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

115821540 is a wasteful number, since it uses less digits than its factorization.

115821540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643468 (or 643463 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 27.

The square root of 115821540 is about 10762.0416278697. The cubic root of 115821540 is about 487.4496673873.

The spelling of 115821540 in words is "one hundred fifteen million, eight hundred twenty-one thousand, five hundred forty".