2685806378649 has 81 divisors (see below), whose sum is σ = 4052690034367. Its totient is φ = 1713993784608.

The previous prime is 2685806378581. The next prime is 2685806378657. The reversal of 2685806378649 is 9468736085862.

The square root of 2685806378649 is 1638843.

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

2685806378649 is a `hidden beast` number, since 2 + 6 + 8 + 580 + 6 + 37 + 8 + 6 + 4 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 2631549062025 + 54257316624 = 1622205^2 + 232932^2 .

It is not a de Polignac number, because 2685806378649 - 2¹⁷ = 2685806247577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2685806378669) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 13633534819 + ... + 13633535015.

Almost surely, 2^{2685806378649} is an apocalyptic number.

2685806378649 is the 1638843-rd square number.

2685806378649 is the 819422-nd centered octagonal number.

It is an amenable number.

2685806378649 is a deficient number, since it is larger than the sum of its proper divisors (1366883655718).

2685806378649 is an frugal number, since it uses more digits than its factorization.

2685806378649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 612 (or 306 counting only the distinct ones).

The product of its (nonzero) digits is 836075520, while the sum is 72.

The spelling of 2685806378649 in words is "two trillion, six hundred eighty-five billion, eight hundred six million, three hundred seventy-eight thousand, six hundred forty-nine".