646431403 has 4 divisors (see below), whose sum is σ = 663902560. Its totient is φ = 628960248.

The previous prime is 646431391. The next prime is 646431469. The reversal of 646431403 is 304134646.

It is a happy number.

646431403 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 304134646 = 2 ⋅152067323.

It is a cyclic number.

It is not a de Polignac number, because 646431403 - 2⁵ = 646431371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646431503) 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, 8735523 + ... + 8735596.

It is an arithmetic number, because the mean of its divisors is an integer number (165975640).

Almost surely, 2^646431403 is an apocalyptic number.

646431403 is a deficient number, since it is larger than the sum of its proper divisors (17471157).

646431403 is a wasteful number, since it uses less digits than its factorization.

646431403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17471156.

The product of its (nonzero) digits is 20736, while the sum is 31.

The square root of 646431403 is about 25425.0152998971. The cubic root of 646431403 is about 864.6509347013.

The spelling of 646431403 in words is "six hundred forty-six million, four hundred thirty-one thousand, four hundred three".