661351 has 4 divisors (see below), whose sum is σ = 700272. Its totient is φ = 622432.

The previous prime is 661343. The next prime is 661361. The reversal of 661351 is 153166.

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 661351 - 2³ = 661343 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 (661321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19435 + ... + 19468.

It is an arithmetic number, because the mean of its divisors is an integer number (175068).

2⁶⁶¹³⁵¹ is an apocalyptic number.

661351 is a deficient number, since it is larger than the sum of its proper divisors (38921).

661351 is a wasteful number, since it uses less digits than its factorization.

661351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38920.

The product of its digits is 540, while the sum is 22.

The square root of 661351 is about 813.2348984150. The cubic root of 661351 is about 87.1252434935.

The spelling of 661351 in words is "six hundred sixty-one thousand, three hundred fifty-one".