6511331781 has 12 divisors (see below), whose sum is σ = 9407960640. Its totient is φ = 4339640040.

The previous prime is 6511331779. The next prime is 6511331797. The reversal of 6511331781 is 1871331156.

It is not a de Polignac number, because 6511331781 - 2¹ = 6511331779 is a prime.

It is a super-2 number, since 2×6511331781² = 84794883124521263922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6511331741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 70365 + ... + 134066.

It is an arithmetic number, because the mean of its divisors is an integer number (783996720).

Almost surely, 2^6511331781 is an apocalyptic number.

It is an amenable number.

6511331781 is a deficient number, since it is larger than the sum of its proper divisors (2896628859).

6511331781 is a wasteful number, since it uses less digits than its factorization.

6511331781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 207976 (or 207973 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 6511331781 is about 80692.8236028459. The cubic root of 6511331781 is about 1867.3394615846.

The spelling of 6511331781 in words is "six billion, five hundred eleven million, three hundred thirty-one thousand, seven hundred eighty-one".