66646949 has 2 divisors, whose sum is σ = 66646950. Its totient is φ = 66646948.

The previous prime is 66646913. The next prime is 66646963. The reversal of 66646949 is 94964666.

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., 47128225 + 19518724 = 6865^2 + 4418^2 .

It is a cyclic number.

It is not a de Polignac number, because 66646949 - 2¹⁶ = 66581413 is a prime.

It is a super-2 number, since 2×66646949² = 8883631622017202, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 66646897 and 66646906.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66646969) 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, 33323474 + 33323475.

It is an arithmetic number, because the mean of its divisors is an integer number (33323475).

Almost surely, 2^66646949 is an apocalyptic number.

It is an amenable number.

66646949 is a deficient number, since it is larger than the sum of its proper divisors (1).

66646949 is an equidigital number, since it uses as much as digits as its factorization.

66646949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1679616, while the sum is 50.

The square root of 66646949 is about 8163.7582644270. The cubic root of 66646949 is about 405.4401534859.

The spelling of 66646949 in words is "sixty-six million, six hundred forty-six thousand, nine hundred forty-nine".