661637289 has 16 divisors (see below), whose sum is σ = 895969152. Its totient is φ = 434249088.

The previous prime is 661637287. The next prime is 661637299. The reversal of 661637289 is 982736166.

It is not a de Polignac number, because 661637289 - 2¹ = 661637287 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661637281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47269 + ... + 59645.

It is an arithmetic number, because the mean of its divisors is an integer number (55998072).

Almost surely, 2^661637289 is an apocalyptic number.

It is an amenable number.

661637289 is a deficient number, since it is larger than the sum of its proper divisors (234331863).

661637289 is a wasteful number, since it uses less digits than its factorization.

661637289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12656.

The product of its digits is 653184, while the sum is 48.

The square root of 661637289 is about 25722.3111131173. The cubic root of 661637289 is about 871.3781342009.

The spelling of 661637289 in words is "six hundred sixty-one million, six hundred thirty-seven thousand, two hundred eighty-nine".