661885949 has 2 divisors, whose sum is σ = 661885950. Its totient is φ = 661885948.

The previous prime is 661885897. The next prime is 661885967. The reversal of 661885949 is 949588166.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 356265625 + 305620324 = 18875^2 + 17482^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661885949 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 661885894 and 661885903.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661885249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330942974 + 330942975.

It is an arithmetic number, because the mean of its divisors is an integer number (330942975).

Almost surely, 2^661885949 is an apocalyptic number.

It is an amenable number.

661885949 is a deficient number, since it is larger than the sum of its proper divisors (1).

661885949 is an equidigital number, since it uses as much as digits as its factorization.

661885949 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3732480, while the sum is 56.

The square root of 661885949 is about 25727.1442060715. The cubic root of 661885949 is about 871.4872824970.

The spelling of 661885949 in words is "six hundred sixty-one million, eight hundred eighty-five thousand, nine hundred forty-nine".