660778371949 has 4 divisors (see below), whose sum is σ = 699647687964. Its totient is φ = 621909055936.

The previous prime is 660778371901. The next prime is 660778371961. The reversal of 660778371949 is 949173877066.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 454019916100 + 206758455849 = 673810^2 + 454707^2 .

It is a cyclic number.

It is not a de Polignac number, because 660778371949 - 2¹⁵ = 660778339181 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 (660770371949) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19434657982 + ... + 19434658015.

It is an arithmetic number, because the mean of its divisors is an integer number (174911921991).

Almost surely, 2^660778371949 is an apocalyptic number.

It is an amenable number.

660778371949 is a deficient number, since it is larger than the sum of its proper divisors (38869316015).

660778371949 is a wasteful number, since it uses less digits than its factorization.

660778371949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38869316014.

The product of its (nonzero) digits is 96018048, while the sum is 67.

The spelling of 660778371949 in words is "six hundred sixty billion, seven hundred seventy-eight million, three hundred seventy-one thousand, nine hundred forty-nine".