66661031 has 4 divisors (see below), whose sum is σ = 66690600. Its totient is φ = 66631464.

The previous prime is 66661009. The next prime is 66661043. The reversal of 66661031 is 13016666.

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 66661031 - 2²² = 62466727 is a prime.

It is a super-2 number, since 2×66661031² = 8887386107965922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66660985 and 66661003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66661631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11096 + ... + 16013.

It is an arithmetic number, because the mean of its divisors is an integer number (16672650).

Almost surely, 2^66661031 is an apocalyptic number.

66661031 is a deficient number, since it is larger than the sum of its proper divisors (29569).

66661031 is a wasteful number, since it uses less digits than its factorization.

66661031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29568.

The product of its (nonzero) digits is 3888, while the sum is 29.

The square root of 66661031 is about 8164.6206892911. The cubic root of 66661031 is about 405.4687069619.

Adding to 66661031 its reverse (13016666), we get a palindrome (79677697).

The spelling of 66661031 in words is "sixty-six million, six hundred sixty-one thousand, thirty-one".