661131263 has 4 divisors (see below), whose sum is σ = 711987528. Its totient is φ = 610275000.

The previous prime is 661131257. The next prime is 661131283. The reversal of 661131263 is 362131166.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 362131166 = 2 ⋅181065583.

It is a cyclic number.

It is not a de Polignac number, because 661131263 - 2⁶ = 661131199 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 (661131223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25428113 + ... + 25428138.

It is an arithmetic number, because the mean of its divisors is an integer number (177996882).

Almost surely, 2^661131263 is an apocalyptic number.

661131263 is a deficient number, since it is larger than the sum of its proper divisors (50856265).

661131263 is a wasteful number, since it uses less digits than its factorization.

661131263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50856264.

The product of its digits is 3888, while the sum is 29.

The square root of 661131263 is about 25712.4729071321. The cubic root of 661131263 is about 871.1559316646.

It can be divided in two parts, 66113 and 1263, that added together give a palindrome (67376).

The spelling of 661131263 in words is "six hundred sixty-one million, one hundred thirty-one thousand, two hundred sixty-three".