640951 has 8 divisors (see below), whose sum is σ = 697680. Its totient is φ = 586368.

The previous prime is 640949. The next prime is 640957. The reversal of 640951 is 159046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640951 - 2¹ = 640949 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 120 + ... + 1138.

It is an arithmetic number, because the mean of its divisors is an integer number (87210).

2⁶⁴⁰⁹⁵¹ is an apocalyptic number.

640951 is a deficient number, since it is larger than the sum of its proper divisors (56729).

640951 is a wasteful number, since it uses less digits than its factorization.

640951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1073.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 640951 is about 800.5941543629. The cubic root of 640951 is about 86.2200512137.

Adding to 640951 its reverse (159046), we get a palindrome (799997).

The spelling of 640951 in words is "six hundred forty thousand, nine hundred fifty-one".