2781740781 has 6 divisors (see below), whose sum is σ = 4018070030. Its totient is φ = 1854493848.

The previous prime is 2781740777. The next prime is 2781740789. The reversal of 2781740781 is 1870471872.

It can be written as a sum of positive squares in only one way, i.e., 2194454025 + 587286756 = 46845^2 + 24234^2 .

It is not a de Polignac number, because 2781740781 - 2² = 2781740777 is a prime.

It is a super-2 number, since 2×2781740781² = 15476163545356979922, 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 (2781740789) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 154541146 + ... + 154541163.

Almost surely, 2^2781740781 is an apocalyptic number.

It is an amenable number.

2781740781 is a deficient number, since it is larger than the sum of its proper divisors (1236329249).

2781740781 is a wasteful number, since it uses less digits than its factorization.

2781740781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309082315 (or 309082312 counting only the distinct ones).

The product of its (nonzero) digits is 175616, while the sum is 45.

The square root of 2781740781 is about 52742.2106191995. The cubic root of 2781740781 is about 1406.3892964474.

The spelling of 2781740781 in words is "two billion, seven hundred eighty-one million, seven hundred forty thousand, seven hundred eighty-one".