1288285661 has 4 divisors (see below), whose sum is σ = 1387384572. Its totient is φ = 1189186752.

The previous prime is 1288285597. The next prime is 1288285667. The reversal of 1288285661 is 1665828821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1665828821 = 97 ⋅17173493.

It can be written as a sum of positive squares in 2 ways, for example, as 787868761 + 500416900 = 28069^2 + 22370^2 .

It is not a de Polignac number, because 1288285661 - 2⁶ = 1288285597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1288285667) 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, 49549436 + ... + 49549461.

It is an arithmetic number, because the mean of its divisors is an integer number (346846143).

Almost surely, 2^1288285661 is an apocalyptic number.

It is an amenable number.

1288285661 is a deficient number, since it is larger than the sum of its proper divisors (99098911).

1288285661 is an equidigital number, since it uses as much as digits as its factorization.

1288285661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99098910.

The product of its digits is 368640, while the sum is 47.

The square root of 1288285661 is about 35892.6964854969. The cubic root of 1288285661 is about 1088.1047955057.

The spelling of 1288285661 in words is "one billion, two hundred eighty-eight million, two hundred eighty-five thousand, six hundred sixty-one".