2581385275561 has 3 divisors (see below), whose sum is σ = 2581386882231. Its totient is φ = 2581383668892.

The previous prime is 2581385275519. The next prime is 2581385275633. The reversal of 2581385275561 is 1655725831852.

The square root of 2581385275561 is 1606669.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 2230186811161 + 351198464400 = 1493381^2 + 592620^2 .

It is not a de Polignac number, because 2581385275561 - 2⁷ = 2581385275433 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2581385275496 and 2581385275505.

It is not an unprimeable number, because it can be changed into a prime (2581385275061) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 803335 + ... + 2410003.

It is an arithmetic number, because the mean of its divisors is an integer number (860462294077).

Almost surely, 2^{2581385275561} is an apocalyptic number.

2581385275561 is the 1606669-th square number.

2581385275561 is the 803335-th centered octagonal number.

It is an amenable number.

2581385275561 is a deficient number, since it is larger than the sum of its proper divisors (1606670).

2581385275561 is an frugal number, since it uses more digits than its factorization.

2581385275561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3213338 (or 1606669 counting only the distinct ones).

The product of its digits is 20160000, while the sum is 58.

The spelling of 2581385275561 in words is "two trillion, five hundred eighty-one billion, three hundred eighty-five million, two hundred seventy-five thousand, five hundred sixty-one".