66861031 has 2 divisors, whose sum is σ = 66861032. Its totient is φ = 66861030.

The previous prime is 66861013. The next prime is 66861043. The reversal of 66861031 is 13016866.

Together with previous prime (66861013) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66861031 - 2⁵ = 66860999 is a prime.

It is a super-2 number, since 2×66861031² = 8940794932765922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 66860984 and 66861002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66861131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33430515 + 33430516.

It is an arithmetic number, because the mean of its divisors is an integer number (33430516).

Almost surely, 2^66861031 is an apocalyptic number.

66861031 is the 5172-nd centered pentagonal number.

66861031 is a deficient number, since it is larger than the sum of its proper divisors (1).

66861031 is an equidigital number, since it uses as much as digits as its factorization.

66861031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 66861031 is about 8176.8594827110. The cubic root of 66861031 is about 405.8738050854.

Adding to 66861031 its reverse (13016866), we get a palindrome (79877897).

The spelling of 66861031 in words is "sixty-six million, eight hundred sixty-one thousand, thirty-one".