661604767 has 8 divisors (see below), whose sum is σ = 680119200. Its totient is φ = 643345920.

The previous prime is 661604747. The next prime is 661604773. The reversal of 661604767 is 767406166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661604767 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 (661604737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 58642 + ... + 69007.

It is an arithmetic number, because the mean of its divisors is an integer number (85014900).

Almost surely, 2^661604767 is an apocalyptic number.

661604767 is a deficient number, since it is larger than the sum of its proper divisors (18514433).

661604767 is a wasteful number, since it uses less digits than its factorization.

661604767 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127793.

The product of its (nonzero) digits is 254016, while the sum is 43.

The square root of 661604767 is about 25721.6789304275. The cubic root of 661604767 is about 871.3638567791.

The spelling of 661604767 in words is "six hundred sixty-one million, six hundred four thousand, seven hundred sixty-seven".