2561678389 has 4 divisors (see below), whose sum is σ = 2562208524. Its totient is φ = 2561148256.

The previous prime is 2561678341. The next prime is 2561678393. The reversal of 2561678389 is 9838761652.

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 1332615025 + 1229063364 = 36505^2 + 35058^2 .

It is a cyclic number.

It is not a de Polignac number, because 2561678389 - 2¹³ = 2561670197 is a prime.

It is a super-3 number, since 3×2561678389³ (a number of 29 digits) contains 333 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561672389) 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, 257752 + ... + 267505.

It is an arithmetic number, because the mean of its divisors is an integer number (640552131).

Almost surely, 2^2561678389 is an apocalyptic number.

It is an amenable number.

2561678389 is a deficient number, since it is larger than the sum of its proper divisors (530135).

2561678389 is an equidigital number, since it uses as much as digits as its factorization.

2561678389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 530134.

The product of its digits is 4354560, while the sum is 55.

The square root of 2561678389 is about 50613.0258826717. The cubic root of 2561678389 is about 1368.2796508659.

The spelling of 2561678389 in words is "two billion, five hundred sixty-one million, six hundred seventy-eight thousand, three hundred eighty-nine".