56661 has 16 divisors (see below), whose sum is σ = 88128. Its totient is φ = 32000.

The previous prime is 56659. The next prime is 56663. The reversal of 56661 is 16665.

56661 = T₇₃ + T₇₄ + ... + T₈₉.

It is an interprime number because it is at equal distance from previous prime (56659) and next prime (56663).

It is a 4-Lehmer number, since φ(56661) divides (56661-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 56661 - 2¹ = 56659 is a prime.

56661 is a lucky number.

It is a nialpdrome in base 16.

It is a zygodrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (56663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 511 + ... + 611.

It is an arithmetic number, because the mean of its divisors is an integer number (5508).

2⁵⁶⁶⁶¹ is an apocalyptic number.

56661 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

56661 is a deficient number, since it is larger than the sum of its proper divisors (31467).

56661 is a wasteful number, since it uses less digits than its factorization.

56661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132.

The product of its digits is 1080, while the sum is 24.

The square root of 56661 is about 238.0357116065. The cubic root of 56661 is about 38.4085647129.

It can be divided in two parts, 56 and 661, that added together give a palindrome (717).

The spelling of 56661 in words is "fifty-six thousand, six hundred sixty-one".