661711605 has 8 divisors (see below), whose sum is σ = 1058738592. Its totient is φ = 352912848.

The previous prime is 661711597. The next prime is 661711657. The reversal of 661711605 is 506117166.

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

It is not a de Polignac number, because 661711605 - 2³ = 661711597 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22057039 + ... + 22057068.

It is an arithmetic number, because the mean of its divisors is an integer number (132342324).

Almost surely, 2^661711605 is an apocalyptic number.

It is an amenable number.

661711605 is a deficient number, since it is larger than the sum of its proper divisors (397026987).

661711605 is a wasteful number, since it uses less digits than its factorization.

661711605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44114115.

The product of its (nonzero) digits is 7560, while the sum is 33.

The square root of 661711605 is about 25723.7556550361. The cubic root of 661711605 is about 871.4107577718.

It can be divided in two parts, 66171 and 1605, that added together give a palindrome (67776).

The spelling of 661711605 in words is "six hundred sixty-one million, seven hundred eleven thousand, six hundred five".