661740858 has 24 divisors (see below), whose sum is σ = 1447175808. Its totient is φ = 218518152.

The previous prime is 661740857. The next prime is 661740883. The reversal of 661740858 is 858047166.

It is a happy number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (661740857) 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 11 ways as a sum of consecutive naturals, for example, 169866 + ... + 173717.

It is an arithmetic number, because the mean of its divisors is an integer number (60298992).

Almost surely, 2^661740858 is an apocalyptic number.

661740858 is an abundant number, since it is smaller than the sum of its proper divisors (785434950).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661740858 is a wasteful number, since it uses less digits than its factorization.

661740858 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343698 (or 343695 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 45.

The square root of 661740858 is about 25724.3242476843. The cubic root of 661740858 is about 871.4235987149.

The spelling of 661740858 in words is "six hundred sixty-one million, seven hundred forty thousand, eight hundred fifty-eight".