2781551991 has 32 divisors (see below), whose sum is σ = 3829524480. Its totient is φ = 1795166816.

The previous prime is 2781551947. The next prime is 2781552013. The reversal of 2781551991 is 1991551872.

It is a cyclic number.

It is not a de Polignac number, because 2781551991 - 2¹⁴ = 2781535607 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2781551991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2781551491) 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 31 ways as a sum of consecutive naturals, for example, 4298830 + ... + 4299476.

It is an arithmetic number, because the mean of its divisors is an integer number (119672640).

Almost surely, 2^2781551991 is an apocalyptic number.

2781551991 is a deficient number, since it is larger than the sum of its proper divisors (1047972489).

2781551991 is a wasteful number, since it uses less digits than its factorization.

2781551991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1043.

The product of its digits is 226800, while the sum is 48.

The square root of 2781551991 is about 52740.4208458749. The cubic root of 2781551991 is about 1406.3574796508.

The spelling of 2781551991 in words is "two billion, seven hundred eighty-one million, five hundred fifty-one thousand, nine hundred ninety-one".