2781217261 has 4 divisors (see below), whose sum is σ = 2781436252. Its totient is φ = 2780998272.

The previous prime is 2781217217. The next prime is 2781217267. The reversal of 2781217261 is 1627121872.

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 1197575236 + 1583642025 = 34606^2 + 39795^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2781217261 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2781217261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2781217267) 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, 89190 + ... + 116263.

It is an arithmetic number, because the mean of its divisors is an integer number (695359063).

Almost surely, 2^2781217261 is an apocalyptic number.

It is an amenable number.

2781217261 is a deficient number, since it is larger than the sum of its proper divisors (218991).

2781217261 is a wasteful number, since it uses less digits than its factorization.

2781217261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218990.

The product of its digits is 18816, while the sum is 37.

The square root of 2781217261 is about 52737.2473779207. The cubic root of 2781217261 is about 1406.3010640328.

The spelling of 2781217261 in words is "two billion, seven hundred eighty-one million, two hundred seventeen thousand, two hundred sixty-one".