660551 has 4 divisors (see below), whose sum is σ = 676704. Its totient is φ = 644400.

The previous prime is 660547. The next prime is 660557. The reversal of 660551 is 155066.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 660551 - 2² = 660547 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 (660557) 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, 8015 + ... + 8096.

It is an arithmetic number, because the mean of its divisors is an integer number (169176).

2⁶⁶⁰⁵⁵¹ is an apocalyptic number.

660551 is a deficient number, since it is larger than the sum of its proper divisors (16153).

660551 is a wasteful number, since it uses less digits than its factorization.

660551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16152.

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 660551 is about 812.7428867729. The cubic root of 660551 is about 87.0900991108.

The spelling of 660551 in words is "six hundred sixty thousand, five hundred fifty-one".