663781261 has 32 divisors (see below), whose sum is σ = 819100800. Its totient is φ = 529562880.

The previous prime is 663781253. The next prime is 663781273. The reversal of 663781261 is 162187366.

It is a happy number.

It is not a de Polignac number, because 663781261 - 2³ = 663781253 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 (663781231) 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 31 ways as a sum of consecutive naturals, for example, 276655 + ... + 279043.

It is an arithmetic number, because the mean of its divisors is an integer number (25596900).

Almost surely, 2^663781261 is an apocalyptic number.

It is an amenable number.

663781261 is a deficient number, since it is larger than the sum of its proper divisors (155319539).

663781261 is a wasteful number, since it uses less digits than its factorization.

663781261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2509.

The product of its digits is 72576, while the sum is 40.

The square root of 663781261 is about 25763.9527440958. The cubic root of 663781261 is about 872.3183250771.

The spelling of 663781261 in words is "six hundred sixty-three million, seven hundred eighty-one thousand, two hundred sixty-one".