115205821 has 4 divisors (see below), whose sum is σ = 121982652. Its totient is φ = 108428992.

The previous prime is 115205813. The next prime is 115205863. The reversal of 115205821 is 128502511.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 83722500 + 31483321 = 9150^2 + 5611^2 .

It is not a de Polignac number, because 115205821 - 2³ = 115205813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (115205801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3388390 + ... + 3388423.

It is an arithmetic number, because the mean of its divisors is an integer number (30495663).

Almost surely, 2^115205821 is an apocalyptic number.

It is an amenable number.

115205821 is a deficient number, since it is larger than the sum of its proper divisors (6776831).

115205821 is an equidigital number, since it uses as much as digits as its factorization.

115205821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6776830.

The product of its (nonzero) digits is 800, while the sum is 25.

The square root of 115205821 is about 10733.3974584006. The cubic root of 115205821 is about 486.5843549934.

The spelling of 115205821 in words is "one hundred fifteen million, two hundred five thousand, eight hundred twenty-one".