661166101 has 2 divisors, whose sum is σ = 661166102. Its totient is φ = 661166100.

The previous prime is 661166069. The next prime is 661166141. The reversal of 661166101 is 101661166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 657922500 + 3243601 = 25650^2 + 1801^2 .

It is a cyclic number.

It is not a de Polignac number, because 661166101 - 2⁵ = 661166069 is a prime.

It is a super-2 number, since 2×661166101² = 874281226223084402, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 661166101.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661166141) 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 as a sum of consecutive naturals, namely, 330583050 + 330583051.

It is an arithmetic number, because the mean of its divisors is an integer number (330583051).

Almost surely, 2^661166101 is an apocalyptic number.

It is an amenable number.

661166101 is a deficient number, since it is larger than the sum of its proper divisors (1).

661166101 is an equidigital number, since it uses as much as digits as its factorization.

661166101 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 661166101 is about 25713.1503515225. The cubic root of 661166101 is about 871.1712331128.

It can be divided in two parts, 661166 and 101, that multiplied together give a palindrome (66777766).

The spelling of 661166101 in words is "six hundred sixty-one million, one hundred sixty-six thousand, one hundred one".