660630521 has 4 divisors (see below), whose sum is σ = 663068544. Its totient is φ = 658192500.

The previous prime is 660630497. The next prime is 660630533. The reversal of 660630521 is 125036066.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 125036066 = 2 ⋅62518033.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-660630521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (660650521) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1218605 + ... + 1219146.

It is an arithmetic number, because the mean of its divisors is an integer number (165767136).

Almost surely, 2^660630521 is an apocalyptic number.

It is an amenable number.

660630521 is a deficient number, since it is larger than the sum of its proper divisors (2438023).

660630521 is a wasteful number, since it uses less digits than its factorization.

660630521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2438022.

The product of its (nonzero) digits is 6480, while the sum is 29.

The square root of 660630521 is about 25702.7337262012. The cubic root of 660630521 is about 870.9359377609.

Adding to 660630521 its reverse (125036066), we get a palindrome (785666587).

The spelling of 660630521 in words is "six hundred sixty million, six hundred thirty thousand, five hundred twenty-one".