515661 has 8 divisors (see below), whose sum is σ = 728064. Its totient is φ = 323520.

The previous prime is 515653. The next prime is 515663. The reversal of 515661 is 166515.

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

It is not a de Polignac number, because 515661 - 2³ = 515653 is a prime.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 515661.

It is not an unprimeable number, because it can be changed into a prime (515663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5005 + ... + 5106.

It is an arithmetic number, because the mean of its divisors is an integer number (91008).

2⁵¹⁵⁶⁶¹ is an apocalyptic number.

515661 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

515661 is a deficient number, since it is larger than the sum of its proper divisors (212403).

515661 is a wasteful number, since it uses less digits than its factorization.

515661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10131.

The product of its digits is 900, while the sum is 24.

The square root of 515661 is about 718.0953975622. The cubic root of 515661 is about 80.1902244083.

It can be divided in two parts, 515 and 661, that added together give a triangular number (1176 = T₄₈).

The spelling of 515661 in words is "five hundred fifteen thousand, six hundred sixty-one".