661655687 has 8 divisors (see below), whose sum is σ = 824921472. Its totient is φ = 515575800.

The previous prime is 661655671. The next prime is 661655693. The reversal of 661655687 is 786556166.

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

It is a cyclic number.

It is not a de Polignac number, because 661655687 - 2⁴ = 661655671 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 (661655647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4296389 + ... + 4296542.

It is an arithmetic number, because the mean of its divisors is an integer number (103115184).

Almost surely, 2^661655687 is an apocalyptic number.

661655687 is a deficient number, since it is larger than the sum of its proper divisors (163265785).

661655687 is a wasteful number, since it uses less digits than its factorization.

661655687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8592949.

The product of its digits is 1814400, while the sum is 50.

The square root of 661655687 is about 25722.6687379051. The cubic root of 661655687 is about 871.3862108649.

The spelling of 661655687 in words is "six hundred sixty-one million, six hundred fifty-five thousand, six hundred eighty-seven".