660605661 has 24 divisors (see below), whose sum is σ = 1020911840. Its totient is φ = 410378400.

The previous prime is 660605657. The next prime is 660605681. The reversal of 660605661 is 166506066.

It is not a de Polignac number, because 660605661 - 2² = 660605657 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660605681) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21235 + ... + 42096.

Almost surely, 2^660605661 is an apocalyptic number.

660605661 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

660605661 is a deficient number, since it is larger than the sum of its proper divisors (360306179).

660605661 is a wasteful number, since it uses less digits than its factorization.

660605661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63417 (or 63414 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 36.

The square root of 660605661 is about 25702.2501155055. The cubic root of 660605661 is about 870.9250129760.

The spelling of 660605661 in words is "six hundred sixty million, six hundred five thousand, six hundred sixty-one".