661666606 has 8 divisors (see below), whose sum is σ = 993845160. Its totient is φ = 330384888.

The previous prime is 661666601. The next prime is 661666613. The reversal of 661666606 is 606666166.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661666601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 222361 + ... + 225316.

It is an arithmetic number, because the mean of its divisors is an integer number (124230645).

Almost surely, 2^661666606 is an apocalyptic number.

661666606 is a deficient number, since it is larger than the sum of its proper divisors (332178554).

661666606 is a wasteful number, since it uses less digits than its factorization.

661666606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 448418.

The product of its (nonzero) digits is 279936, while the sum is 43.

The square root of 661666606 is about 25722.8809817252. The cubic root of 661666606 is about 871.3910042008.

The spelling of 661666606 in words is "six hundred sixty-one million, six hundred sixty-six thousand, six hundred six".