2115021981 has 4 divisors (see below), whose sum is σ = 2820029312. Its totient is φ = 1410014652.

The previous prime is 2115021973. The next prime is 2115021983. The reversal of 2115021981 is 1891205112.

2115021981 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 2115021981 - 2³ = 2115021973 is a prime.

It is a super-2 number, since 2×2115021981² = 8946635960226328722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2115021983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 352503661 + ... + 352503666.

It is an arithmetic number, because the mean of its divisors is an integer number (705007328).

Almost surely, 2^2115021981 is an apocalyptic number.

It is an amenable number.

2115021981 is a deficient number, since it is larger than the sum of its proper divisors (705007331).

2115021981 is an equidigital number, since it uses as much as digits as its factorization.

2115021981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 705007330.

The product of its (nonzero) digits is 1440, while the sum is 30.

The square root of 2115021981 is about 45989.3681300363. The cubic root of 2115021981 is about 1283.6253789874.

The spelling of 2115021981 in words is "two billion, one hundred fifteen million, twenty-one thousand, nine hundred eighty-one".