667857649 has 2 divisors, whose sum is σ = 667857650. Its totient is φ = 667857648.

The previous prime is 667857637. The next prime is 667857653. The reversal of 667857649 is 946758766.

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., 456591424 + 211266225 = 21368^2 + 14535^2 .

It is a cyclic number.

It is not a de Polignac number, because 667857649 - 2²¹ = 665760497 is a prime.

It is a super-3 number, since 3×667857649³ (a number of 27 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 667857593 and 667857602.

It is not a weakly prime, because it can be changed into another prime (667858649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333928824 + 333928825.

It is an arithmetic number, because the mean of its divisors is an integer number (333928825).

Almost surely, 2^667857649 is an apocalyptic number.

It is an amenable number.

667857649 is a deficient number, since it is larger than the sum of its proper divisors (1).

667857649 is an equidigital number, since it uses as much as digits as its factorization.

667857649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15240960, while the sum is 58.

The square root of 667857649 is about 25842.9419571379. The cubic root of 667857649 is about 874.1003647134.

The spelling of 667857649 in words is "six hundred sixty-seven million, eight hundred fifty-seven thousand, six hundred forty-nine".