6918777947449 has 3 divisors (see below), whose sum is σ = 6918780577807. Its totient is φ = 6918775317092.

The previous prime is 6918777947399. The next prime is 6918777947509. The reversal of 6918777947449 is 9447497778196.

The square root of 6918777947449 is 2630357.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 5403741914025 + 1515036033424 = 2324595^2 + 1230868^2 .

It is not a de Polignac number, because 6918777947449 - 2⁷ = 6918777947321 is a prime.

It is a super-2 number, since 2×6918777947449² (a number of 26 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6918777947149) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1315179 + ... + 3945535.

Almost surely, 2^{6918777947449} is an apocalyptic number.

6918777947449 is the 2630357-th square number.

6918777947449 is the 1315179-th centered octagonal number.

It is an amenable number.

6918777947449 is a deficient number, since it is larger than the sum of its proper divisors (2630358).

6918777947449 is an frugal number, since it uses more digits than its factorization.

6918777947449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5260714 (or 2630357 counting only the distinct ones).

The product of its digits is 5377010688, while the sum is 82.

The spelling of 6918777947449 in words is "six trillion, nine hundred eighteen billion, seven hundred seventy-seven million, nine hundred forty-seven thousand, four hundred forty-nine".