66531 has 8 divisors (see below), whose sum is σ = 90304. Its totient is φ = 43560.

The previous prime is 66529. The next prime is 66533. The reversal of 66531 is 13566.

It is an interprime number because it is at equal distance from previous prime (66529) and next prime (66533).

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

It is not a de Polignac number, because 66531 - 2¹ = 66529 is a prime.

It is a super-2 number, since 2×66531² = 8852747922, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 9.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 66498 and 66507.

It is not an unprimeable number, because it can be changed into a prime (66533) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36 + ... + 366.

It is an arithmetic number, because the mean of its divisors is an integer number (11288).

2⁶⁶⁵³¹ is an apocalyptic number.

66531 is a deficient number, since it is larger than the sum of its proper divisors (23773).

66531 is a wasteful number, since it uses less digits than its factorization.

66531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401.

The product of its digits is 540, while the sum is 21.

The square root of 66531 is about 257.9360385832. The cubic root of 66531 is about 40.5204895561.

It can be divided in two parts, 665 and 31, that added together give a palindrome (696).

The spelling of 66531 in words is "sixty-six thousand, five hundred thirty-one".