1285565581 has 4 divisors (see below), whose sum is σ = 1289249500. Its totient is φ = 1281881664.

The previous prime is 1285565569. The next prime is 1285565597. The reversal of 1285565581 is 1855655821.

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 1040643081 + 244922500 = 32259^2 + 15650^2 .

It is a cyclic number.

It is not a de Polignac number, because 1285565581 - 2⁹ = 1285565069 is a prime.

It is a super-2 number, since 2×1285565581² = 3305357726103735122, 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 (1285560581) 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, 1841436 + ... + 1842133.

It is an arithmetic number, because the mean of its divisors is an integer number (322312375).

Almost surely, 2^1285565581 is an apocalyptic number.

It is an amenable number.

1285565581 is a deficient number, since it is larger than the sum of its proper divisors (3683919).

1285565581 is an equidigital number, since it uses as much as digits as its factorization.

1285565581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3683918.

The product of its digits is 480000, while the sum is 46.

The square root of 1285565581 is about 35854.7846319009. The cubic root of 1285565581 is about 1087.3384495305.

It can be divided in two parts, 1 and 285565581, that added together give a palindrome (285565582).

The spelling of 1285565581 in words is "one billion, two hundred eighty-five million, five hundred sixty-five thousand, five hundred eighty-one".