661364573 has 2 divisors, whose sum is σ = 661364574. Its totient is φ = 661364572.

The previous prime is 661364567. The next prime is 661364591. The reversal of 661364573 is 375463166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 661364089 + 484 = 25717^2 + 22^2 .

It is a cyclic number.

It is not a de Polignac number, because 661364573 - 2¹⁴ = 661348189 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 661364573.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661364593) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330682286 + 330682287.

It is an arithmetic number, because the mean of its divisors is an integer number (330682287).

Almost surely, 2^661364573 is an apocalyptic number.

It is an amenable number.

661364573 is a deficient number, since it is larger than the sum of its proper divisors (1).

661364573 is an equidigital number, since it uses as much as digits as its factorization.

661364573 is an evil number, because the sum of its binary digits is even.

The product of its digits is 272160, while the sum is 41.

The square root of 661364573 is about 25717.0094101161. The cubic root of 661364573 is about 871.2583951732.

The spelling of 661364573 in words is "six hundred sixty-one million, three hundred sixty-four thousand, five hundred seventy-three".