661306445 has 4 divisors (see below), whose sum is σ = 793567740. Its totient is φ = 529045152.

The previous prime is 661306441. The next prime is 661306447. The reversal of 661306445 is 544603166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 544603166 = 2 ⋅272301583.

It can be written as a sum of positive squares in 2 ways, for example, as 452966089 + 208340356 = 21283^2 + 14434^2 .

It is a cyclic number.

It is not a de Polignac number, because 661306445 - 2² = 661306441 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661306441) 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 3 ways as a sum of consecutive naturals, for example, 66130640 + ... + 66130649.

It is an arithmetic number, because the mean of its divisors is an integer number (198391935).

Almost surely, 2^661306445 is an apocalyptic number.

It is an amenable number.

661306445 is a deficient number, since it is larger than the sum of its proper divisors (132261295).

661306445 is a wasteful number, since it uses less digits than its factorization.

661306445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132261294.

The product of its (nonzero) digits is 51840, while the sum is 35.

The square root of 661306445 is about 25715.8792383228. The cubic root of 661306445 is about 871.2328691654.

The spelling of 661306445 in words is "six hundred sixty-one million, three hundred six thousand, four hundred forty-five".