661958 has 8 divisors (see below), whose sum is σ = 1083240. Its totient is φ = 300880.

The previous prime is 661951. The next prime is 661961. The reversal of 661958 is 859166.

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

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661951) by changing a digit.

661958 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15023 + ... + 15066.

It is an arithmetic number, because the mean of its divisors is an integer number (135405).

2⁶⁶¹⁹⁵⁸ is an apocalyptic number.

661958 is a deficient number, since it is larger than the sum of its proper divisors (421282).

661958 is a wasteful number, since it uses less digits than its factorization.

661958 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30102.

The product of its digits is 12960, while the sum is 35.

The square root of 661958 is about 813.6080137265. The cubic root of 661958 is about 87.1518903882.

The spelling of 661958 in words is "six hundred sixty-one thousand, nine hundred fifty-eight".