646589917 has 4 divisors (see below), whose sum is σ = 684624636. Its totient is φ = 608555200.

The previous prime is 646589897. The next prime is 646589921. The reversal of 646589917 is 719985646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 719985646 = 2 ⋅359992823.

It can be written as a sum of positive squares in 2 ways, for example, as 405377956 + 241211961 = 20134^2 + 15531^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646589917 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646589117) 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, 19017334 + ... + 19017367.

It is an arithmetic number, because the mean of its divisors is an integer number (171156159).

Almost surely, 2^646589917 is an apocalyptic number.

It is an amenable number.

646589917 is a deficient number, since it is larger than the sum of its proper divisors (38034719).

646589917 is a wasteful number, since it uses less digits than its factorization.

646589917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38034718.

The product of its digits is 3265920, while the sum is 55.

The square root of 646589917 is about 25428.1323930799. The cubic root of 646589917 is about 864.7216037500.

The spelling of 646589917 in words is "six hundred forty-six million, five hundred eighty-nine thousand, nine hundred seventeen".