661665051 has 8 divisors (see below), whose sum is σ = 980244560. Its totient is φ = 441110016.

The previous prime is 661665049. The next prime is 661665061. The reversal of 661665051 is 150566166.

661665051 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661665051 - 2¹ = 661665049 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661664997 and 661665015.

It is not an unprimeable number, because it can be changed into a prime (661665031) 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, 12253030 + ... + 12253083.

It is an arithmetic number, because the mean of its divisors is an integer number (122530570).

Almost surely, 2^661665051 is an apocalyptic number.

661665051 is a deficient number, since it is larger than the sum of its proper divisors (318579509).

661665051 is a wasteful number, since it uses less digits than its factorization.

661665051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24506122 (or 24506116 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

The square root of 661665051 is about 25722.8507556997. The cubic root of 661665051 is about 871.3903215740.

It can be divided in two parts, 66166 and 5051, that added together give a palindrome (71217).

The spelling of 661665051 in words is "six hundred sixty-one million, six hundred sixty-five thousand, fifty-one".