6491978069 has 4 divisors (see below), whose sum is σ = 6494250060. Its totient is φ = 6489706080.

The previous prime is 6491978047. The next prime is 6491978107. The reversal of 6491978069 is 9608791946.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2128715044 + 4363263025 = 46138^2 + 66055^2 .

It is a cyclic number.

It is not a de Polignac number, because 6491978069 - 2²⁸ = 6223542613 is a prime.

It is a super-3 number, since 3×6491978069³ (a number of 30 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6491977999 and 6491978017.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6491971069) 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, 1131704 + ... + 1137425.

It is an arithmetic number, because the mean of its divisors is an integer number (1623562515).

Almost surely, 2^6491978069 is an apocalyptic number.

It is an amenable number.

6491978069 is a deficient number, since it is larger than the sum of its proper divisors (2271991).

6491978069 is a wasteful number, since it uses less digits than its factorization.

6491978069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2271990.

The product of its (nonzero) digits is 5878656, while the sum is 59.

The square root of 6491978069 is about 80572.8122197556. The cubic root of 6491978069 is about 1865.4875201276.

The spelling of 6491978069 in words is "six billion, four hundred ninety-one million, nine hundred seventy-eight thousand, sixty-nine".