2645877781 has 4 divisors (see below), whose sum is σ = 2663635500. Its totient is φ = 2628120064.

The previous prime is 2645877779. The next prime is 2645877821. The reversal of 2645877781 is 1877785462.

2645877781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 1272063556 + 1373814225 = 35666^2 + 37065^2 .

It is a cyclic number.

It is not a de Polignac number, because 2645877781 - 2¹ = 2645877779 is a prime.

It is a super-2 number, since 2×2645877781² = 14001338463978967922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2645877701) 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, 8878636 + ... + 8878933.

It is an arithmetic number, because the mean of its divisors is an integer number (665908875).

Almost surely, 2^2645877781 is an apocalyptic number.

It is an amenable number.

2645877781 is a deficient number, since it is larger than the sum of its proper divisors (17757719).

2645877781 is a wasteful number, since it uses less digits than its factorization.

2645877781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17757718.

The product of its digits is 5268480, while the sum is 55.

The square root of 2645877781 is about 51438.0965919230. The cubic root of 2645877781 is about 1383.1095916391.

The spelling of 2645877781 in words is "two billion, six hundred forty-five million, eight hundred seventy-seven thousand, seven hundred eighty-one".