667209997 has 4 divisors (see below), whose sum is σ = 667265440. Its totient is φ = 667154556.

The previous prime is 667209971. The next prime is 667210003. The reversal of 667209997 is 799902766.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-667209997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667206997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1233 + ... + 36550.

It is an arithmetic number, because the mean of its divisors is an integer number (166816360).

Almost surely, 2^667209997 is an apocalyptic number.

It is an amenable number.

667209997 is a deficient number, since it is larger than the sum of its proper divisors (55443).

667209997 is a wasteful number, since it uses less digits than its factorization.

667209997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55442.

The product of its (nonzero) digits is 2571912, while the sum is 55.

The square root of 667209997 is about 25830.4083784984. The cubic root of 667209997 is about 873.8177216761.

The spelling of 667209997 in words is "six hundred sixty-seven million, two hundred nine thousand, nine hundred ninety-seven".