660648381 has 8 divisors (see below), whose sum is σ = 881046144. Its totient is φ = 440341440.

The previous prime is 660648299. The next prime is 660648383. The reversal of 660648381 is 183846066.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-660648381 is a prime.

It is a super-2 number, since 2×660648381² = 872912566635842322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660648383) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3381 + ... + 36506.

It is an arithmetic number, because the mean of its divisors is an integer number (110130768).

Almost surely, 2^660648381 is an apocalyptic number.

It is an amenable number.

660648381 is a deficient number, since it is larger than the sum of its proper divisors (220397763).

660648381 is a wasteful number, since it uses less digits than its factorization.

660648381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45411.

The product of its (nonzero) digits is 165888, while the sum is 42.

The square root of 660648381 is about 25703.0811577134. The cubic root of 660648381 is about 870.9437862103.

The spelling of 660648381 in words is "six hundred sixty million, six hundred forty-eight thousand, three hundred eighty-one".