2561816817485 has 4 divisors (see below), whose sum is σ = 3074180180988. Its totient is φ = 2049453453984.

The previous prime is 2561816817479. The next prime is 2561816817523. The reversal of 2561816817485 is 5847186181652.

It is a happy number.

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 1720454578921 + 841362238564 = 1311661^2 + 917258^2 .

It is a cyclic number.

It is not a de Polignac number, because 2561816817485 - 2⁶ = 2561816817421 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 256181681744 + ... + 256181681753.

It is an arithmetic number, because the mean of its divisors is an integer number (768545045247).

Almost surely, 2^{2561816817485} is an apocalyptic number.

It is an amenable number.

2561816817485 is a deficient number, since it is larger than the sum of its proper divisors (512363363503).

2561816817485 is an equidigital number, since it uses as much as digits as its factorization.

2561816817485 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 512363363502.

The product of its digits is 25804800, while the sum is 62.

The spelling of 2561816817485 in words is "two trillion, five hundred sixty-one billion, eight hundred sixteen million, eight hundred seventeen thousand, four hundred eighty-five".