2115811581 has 16 divisors (see below), whose sum is σ = 3053366400. Its totient is φ = 1295490240.

The previous prime is 2115811571. The next prime is 2115811583. The reversal of 2115811581 is 1851185112.

It is not a de Polignac number, because 2115811581 - 2⁹ = 2115811069 is a prime.

It is a super-2 number, since 2×2115811581² = 8953317292587439122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2115811583) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 128550 + ... + 144071.

It is an arithmetic number, because the mean of its divisors is an integer number (190835400).

Almost surely, 2^2115811581 is an apocalyptic number.

It is an amenable number.

2115811581 is a deficient number, since it is larger than the sum of its proper divisors (937554819).

2115811581 is a wasteful number, since it uses less digits than its factorization.

2115811581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272836.

The product of its digits is 3200, while the sum is 33.

The square root of 2115811581 is about 45997.9519217976. The cubic root of 2115811581 is about 1283.7850975002.

Adding to 2115811581 its reverse (1851185112), we get a palindrome (3966996693).

The spelling of 2115811581 in words is "two billion, one hundred fifteen million, eight hundred eleven thousand, five hundred eighty-one".