2778640581 has 4 divisors (see below), whose sum is σ = 3704854112. Its totient is φ = 1852427052.

The previous prime is 2778640547. The next prime is 2778640583. The reversal of 2778640581 is 1850468772.

2778640581 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 2778640581 - 2¹⁴ = 2778624197 is a prime.

It is a super-2 number, since 2×2778640581² = 15441686956760035122, which contains 22 as substring.

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 2778640581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2778640583) 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, 463106761 + ... + 463106766.

It is an arithmetic number, because the mean of its divisors is an integer number (926213528).

Almost surely, 2^2778640581 is an apocalyptic number.

It is an amenable number.

2778640581 is a deficient number, since it is larger than the sum of its proper divisors (926213531).

2778640581 is an equidigital number, since it uses as much as digits as its factorization.

2778640581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 926213530.

The product of its (nonzero) digits is 752640, while the sum is 48.

The square root of 2778640581 is about 52712.8123040310. The cubic root of 2778640581 is about 1405.8666370541.

The spelling of 2778640581 in words is "two billion, seven hundred seventy-eight million, six hundred forty thousand, five hundred eighty-one".