661907 has 4 divisors (see below), whose sum is σ = 665256. Its totient is φ = 658560.

The previous prime is 661897. The next prime is 661909. The reversal of 661907 is 709166.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661907 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661907.

It is not an unprimeable number, because it can be changed into a prime (661909) 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, 1358 + ... + 1779.

It is an arithmetic number, because the mean of its divisors is an integer number (166314).

2⁶⁶¹⁹⁰⁷ is an apocalyptic number.

661907 is a deficient number, since it is larger than the sum of its proper divisors (3349).

661907 is a wasteful number, since it uses less digits than its factorization.

661907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3348.

The product of its (nonzero) digits is 2268, while the sum is 29.

The square root of 661907 is about 813.5766712486. The cubic root of 661907 is about 87.1496521493.

The spelling of 661907 in words is "six hundred sixty-one thousand, nine hundred seven".