2670781991 has 4 divisors (see below), whose sum is σ = 2827886832. Its totient is φ = 2513677152.

The previous prime is 2670781979. The next prime is 2670782041. The reversal of 2670781991 is 1991870762.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2670781991 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 (2670781931) 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 3 ways as a sum of consecutive naturals, for example, 78552395 + ... + 78552428.

It is an arithmetic number, because the mean of its divisors is an integer number (706971708).

Almost surely, 2^2670781991 is an apocalyptic number.

2670781991 is a deficient number, since it is larger than the sum of its proper divisors (157104841).

2670781991 is a wasteful number, since it uses less digits than its factorization.

2670781991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157104840.

The product of its (nonzero) digits is 381024, while the sum is 50.

The square root of 2670781991 is about 51679.6090445739. The cubic root of 2670781991 is about 1387.4355336874.

The spelling of 2670781991 in words is "two billion, six hundred seventy million, seven hundred eighty-one thousand, nine hundred ninety-one".