661398149 has 2 divisors, whose sum is σ = 661398150. Its totient is φ = 661398148.

The previous prime is 661398121. The next prime is 661398161. The reversal of 661398149 is 941893166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 343917025 + 317481124 = 18545^2 + 17818^2 .

It is a cyclic number.

It is not a de Polignac number, because 661398149 - 2¹² = 661394053 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661398119) 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, 330699074 + 330699075.

It is an arithmetic number, because the mean of its divisors is an integer number (330699075).

Almost surely, 2^661398149 is an apocalyptic number.

It is an amenable number.

661398149 is a deficient number, since it is larger than the sum of its proper divisors (1).

661398149 is an equidigital number, since it uses as much as digits as its factorization.

661398149 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 279936, while the sum is 47.

The square root of 661398149 is about 25717.6621993524. The cubic root of 661398149 is about 871.2731388703.

The spelling of 661398149 in words is "six hundred sixty-one million, three hundred ninety-eight thousand, one hundred forty-nine".