646401001 has 4 divisors (see below), whose sum is σ = 646452100. Its totient is φ = 646349904.

The previous prime is 646400959. The next prime is 646401043. The reversal of 646401001 is 100104646.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 100104646 = 2 ⋅50052323.

It is an interprime number because it is at equal distance from previous prime (646400959) and next prime (646401043).

It can be written as a sum of positive squares in 2 ways, for example, as 342805225 + 303595776 = 18515^2 + 17424^2 .

It is a cyclic number.

It is not a de Polignac number, because 646401001 - 2²⁹ = 109530089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646401061) 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, 8995 + ... + 37063.

It is an arithmetic number, because the mean of its divisors is an integer number (161613025).

Almost surely, 2^646401001 is an apocalyptic number.

It is an amenable number.

646401001 is a deficient number, since it is larger than the sum of its proper divisors (51099).

646401001 is a wasteful number, since it uses less digits than its factorization.

646401001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51098.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 646401001 is about 25424.4174171209. The cubic root of 646401001 is about 864.6373794967.

Adding to 646401001 its reverse (100104646), we get a palindrome (746505647).

The spelling of 646401001 in words is "six hundred forty-six million, four hundred one thousand, one".