661202111 has 2 divisors, whose sum is σ = 661202112. Its totient is φ = 661202110.

The previous prime is 661202107. The next prime is 661202123. The reversal of 661202111 is 111202166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661202111 - 2² = 661202107 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661202161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330601055 + 330601056.

It is an arithmetic number, because the mean of its divisors is an integer number (330601056).

Almost surely, 2^661202111 is an apocalyptic number.

661202111 is a deficient number, since it is larger than the sum of its proper divisors (1).

661202111 is an equidigital number, since it uses as much as digits as its factorization.

661202111 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 661202111 is about 25713.8505673499. The cubic root of 661202111 is about 871.1870487586.

Adding to 661202111 its reverse (111202166), we get a palindrome (772404277).

Subtracting from 661202111 its reverse (111202166), we obtain a palindrome (549999945).

The spelling of 661202111 in words is "six hundred sixty-one million, two hundred two thousand, one hundred eleven".