661129065 has 24 divisors (see below), whose sum is σ = 1213367688. Its totient is φ = 331860480.

The previous prime is 661129057. The next prime is 661129069. The reversal of 661129065 is 560921166.

It can be written as a sum of positive squares in 4 ways, for example, as 161874729 + 499254336 = 12723^2 + 22344^2 .

It is not a de Polignac number, because 661129065 - 2³ = 661129057 is a prime.

It is a super-3 number, since 3×661129065³ (a number of 27 digits) contains 333 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (661129069) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 431346 + ... + 432875.

It is an arithmetic number, because the mean of its divisors is an integer number (50556987).

Almost surely, 2^661129065 is an apocalyptic number.

It is an amenable number.

661129065 is a deficient number, since it is larger than the sum of its proper divisors (552238623).

661129065 is a wasteful number, since it uses less digits than its factorization.

661129065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 864249 (or 864246 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The square root of 661129065 is about 25712.4301651944. The cubic root of 661129065 is about 871.1549662472.

The spelling of 661129065 in words is "six hundred sixty-one million, one hundred twenty-nine thousand, sixty-five".