661378229 has 2 divisors, whose sum is σ = 661378230. Its totient is φ = 661378228.

The previous prime is 661378213. The next prime is 661378241. The reversal of 661378229 is 922873166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 610584100 + 50794129 = 24710^2 + 7127^2 .

It is a cyclic number.

It is not a de Polignac number, because 661378229 - 2⁴ = 661378213 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 661378229.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661378129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330689114 + 330689115.

It is an arithmetic number, because the mean of its divisors is an integer number (330689115).

Almost surely, 2^661378229 is an apocalyptic number.

It is an amenable number.

661378229 is a deficient number, since it is larger than the sum of its proper divisors (1).

661378229 is an equidigital number, since it uses as much as digits as its factorization.

661378229 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 44.

The square root of 661378229 is about 25717.2749139562. The cubic root of 661378229 is about 871.2643917764.

The spelling of 661378229 in words is "six hundred sixty-one million, three hundred seventy-eight thousand, two hundred twenty-nine".