646951 has 4 divisors (see below), whose sum is σ = 648712. Its totient is φ = 645192.

The previous prime is 646937. The next prime is 646957. The reversal of 646951 is 159646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 159646 = 2 ⋅79823.

It is a cyclic number.

It is not a de Polignac number, because 646951 - 2⁷ = 646823 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646957) 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 3 ways as a sum of consecutive naturals, for example, 96 + ... + 1141.

It is an arithmetic number, because the mean of its divisors is an integer number (162178).

2⁶⁴⁶⁹⁵¹ is an apocalyptic number.

646951 is a deficient number, since it is larger than the sum of its proper divisors (1761).

646951 is a wasteful number, since it uses less digits than its factorization.

646951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1760.

The product of its digits is 6480, while the sum is 31.

The square root of 646951 is about 804.3326426299. The cubic root of 646951 is about 86.4882539432.

The spelling of 646951 in words is "six hundred forty-six thousand, nine hundred fifty-one".