2578781 has 4 divisors (see below), whose sum is σ = 2730492. Its totient is φ = 2427072.

The previous prime is 2578759. The next prime is 2578787. The reversal of 2578781 is 1878752.

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 1276900 + 1301881 = 1130^2 + 1141^2 .

It is a cyclic number.

It is not a de Polignac number, because 2578781 - 2⁶ = 2578717 is a prime.

It is a super-2 number, since 2×2578781² = 13300222891922, 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 (2578787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75830 + ... + 75863.

It is an arithmetic number, because the mean of its divisors is an integer number (682623).

2^2578781 is an apocalyptic number.

It is an amenable number.

2578781 is a deficient number, since it is larger than the sum of its proper divisors (151711).

2578781 is a wasteful number, since it uses less digits than its factorization.

2578781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151710.

The product of its digits is 31360, while the sum is 38.

The square root of 2578781 is about 1605.8583374632. The cubic root of 2578781 is about 137.1317928305.

The spelling of 2578781 in words is "two million, five hundred seventy-eight thousand, seven hundred eighty-one".