640967 has 2 divisors, whose sum is σ = 640968. Its totient is φ = 640966.

The previous prime is 640963. The next prime is 640973. The reversal of 640967 is 769046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640967 - 2² = 640963 is a prime.

It is a super-3 number, since 3×640967³ = 790002137625333189, which contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320483 + 320484.

It is an arithmetic number, because the mean of its divisors is an integer number (320484).

2⁶⁴⁰⁹⁶⁷ is an apocalyptic number.

640967 is a deficient number, since it is larger than the sum of its proper divisors (1).

640967 is an equidigital number, since it uses as much as digits as its factorization.

640967 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 32.

The square root of 640967 is about 800.6041468791. The cubic root of 640967 is about 86.2207686421.

The spelling of 640967 in words is "six hundred forty thousand, nine hundred sixty-seven".