1288207661 has 8 divisors (see below), whose sum is σ = 1396613400. Its totient is φ = 1181132352.

The previous prime is 1288207649. The next prime is 1288207721. The reversal of 1288207661 is 1667028821.

It can be written as a sum of positive squares in 4 ways, for example, as 5851561 + 1282356100 = 2419^2 + 35810^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1288207661 - 2⁶ = 1288207597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1288207601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 330590 + ... + 334463.

It is an arithmetic number, because the mean of its divisors is an integer number (174576675).

Almost surely, 2^1288207661 is an apocalyptic number.

It is an amenable number.

1288207661 is a deficient number, since it is larger than the sum of its proper divisors (108405739).

1288207661 is a wasteful number, since it uses less digits than its factorization.

1288207661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 665215.

The product of its (nonzero) digits is 64512, while the sum is 41.

The square root of 1288207661 is about 35891.6098970219. The cubic root of 1288207661 is about 1088.0828350846.

The spelling of 1288207661 in words is "one billion, two hundred eighty-eight million, two hundred seven thousand, six hundred sixty-one".