667645949 has 2 divisors, whose sum is σ = 667645950. Its totient is φ = 667645948.

The previous prime is 667645943. The next prime is 667645961. The reversal of 667645949 is 949546766.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 579942724 + 87703225 = 24082^2 + 9365^2 .

It is a cyclic number.

It is not a de Polignac number, because 667645949 - 2⁴ = 667645933 is a prime.

It is a super-2 number, since 2×667645949² = 891502226432221202, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 667645894 and 667645903.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (667645943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333822974 + 333822975.

It is an arithmetic number, because the mean of its divisors is an integer number (333822975).

Almost surely, 2^667645949 is an apocalyptic number.

It is an amenable number.

667645949 is a deficient number, since it is larger than the sum of its proper divisors (1).

667645949 is an equidigital number, since it uses as much as digits as its factorization.

667645949 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9797760, while the sum is 56.

The square root of 667645949 is about 25838.8457366036. The cubic root of 667645949 is about 874.0079964254.

It can be divided in two parts, 6676 and 45949, that added together give a palindrome (52625).

The spelling of 667645949 in words is "six hundred sixty-seven million, six hundred forty-five thousand, nine hundred forty-nine".