2115815781 has 8 divisors (see below), whose sum is σ = 2826632160. Its totient is φ = 1407771632.

The previous prime is 2115815759. The next prime is 2115815789. The reversal of 2115815781 is 1875185112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2115815781 - 2⁶ = 2115815717 is a prime.

It is a super-2 number, since 2×2115815781² = 8953352838257279922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2115815789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 691275 + ... + 694328.

It is an arithmetic number, because the mean of its divisors is an integer number (353329020).

Almost surely, 2^2115815781 is an apocalyptic number.

It is an amenable number.

2115815781 is a deficient number, since it is larger than the sum of its proper divisors (710816379).

2115815781 is a wasteful number, since it uses less digits than its factorization.

2115815781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1386115.

The product of its digits is 22400, while the sum is 39.

The square root of 2115815781 is about 45997.9975759815. The cubic root of 2115815781 is about 1283.7859469605.

The spelling of 2115815781 in words is "two billion, one hundred fifteen million, eight hundred fifteen thousand, seven hundred eighty-one".