661899986269 has 2 divisors, whose sum is σ = 661899986270. Its totient is φ = 661899986268.

The previous prime is 661899986261. The next prime is 661899986327. The reversal of 661899986269 is 962689998166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 592956981369 + 68943004900 = 770037^2 + 262570^2 .

It is a cyclic number.

It is not a de Polignac number, because 661899986269 - 2³ = 661899986261 is a prime.

It is a super-2 number, since 2×661899986269² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661899986261) 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, 330949993134 + 330949993135.

It is an arithmetic number, because the mean of its divisors is an integer number (330949993135).

Almost surely, 2^661899986269 is an apocalyptic number.

It is an amenable number.

661899986269 is a deficient number, since it is larger than the sum of its proper divisors (1).

661899986269 is an equidigital number, since it uses as much as digits as its factorization.

661899986269 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1088391168, while the sum is 79.

The spelling of 661899986269 in words is "six hundred sixty-one billion, eight hundred ninety-nine million, nine hundred eighty-six thousand, two hundred sixty-nine".