661523 has 8 divisors (see below), whose sum is σ = 715920. Its totient is φ = 609120.

The previous prime is 661517. The next prime is 661541. The reversal of 661523 is 325166.

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

It is a cyclic number.

It is not a de Polignac number, because 661523 - 2⁶ = 661459 is a prime.

It is a super-2 number, since 2×661523² = 875225359058, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 233 + ... + 1173.

It is an arithmetic number, because the mean of its divisors is an integer number (89490).

2⁶⁶¹⁵²³ is an apocalyptic number.

661523 is a deficient number, since it is larger than the sum of its proper divisors (54397).

661523 is a wasteful number, since it uses less digits than its factorization.

661523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 997.

The product of its digits is 1080, while the sum is 23.

The square root of 661523 is about 813.3406420437. The cubic root of 661523 is about 87.1327958336.

Adding to 661523 its reverse (325166), we get a palindrome (986689).

The spelling of 661523 in words is "six hundred sixty-one thousand, five hundred twenty-three".