661645505 has 8 divisors (see below), whose sum is σ = 795607872. Its totient is φ = 528227568.

The previous prime is 661645487. The next prime is 661645519. The reversal of 661645505 is 505546166.

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 661645505 - 2⁶ = 661645441 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 133427 + ... + 138296.

It is an arithmetic number, because the mean of its divisors is an integer number (99450984).

Almost surely, 2^661645505 is an apocalyptic number.

It is an amenable number.

661645505 is a deficient number, since it is larger than the sum of its proper divisors (133962367).

661645505 is a wasteful number, since it uses less digits than its factorization.

661645505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272215.

The product of its (nonzero) digits is 108000, while the sum is 38.

The square root of 661645505 is about 25722.4708183331. The cubic root of 661645505 is about 871.3817410175.

The spelling of 661645505 in words is "six hundred sixty-one million, six hundred forty-five thousand, five hundred five".