646768129 has 4 divisors (see below), whose sum is σ = 739163584. Its totient is φ = 554372676.

The previous prime is 646768099. The next prime is 646768147. The reversal of 646768129 is 921867646.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 646768129 - 2¹³ = 646759937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646768229) 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, 46197717 + ... + 46197730.

It is an arithmetic number, because the mean of its divisors is an integer number (184790896).

Almost surely, 2^646768129 is an apocalyptic number.

It is an amenable number.

646768129 is a deficient number, since it is larger than the sum of its proper divisors (92395455).

646768129 is an equidigital number, since it uses as much as digits as its factorization.

646768129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92395454.

The product of its digits is 870912, while the sum is 49.

The square root of 646768129 is about 25431.6363806972. The cubic root of 646768129 is about 864.8010408123.

The spelling of 646768129 in words is "six hundred forty-six million, seven hundred sixty-eight thousand, one hundred twenty-nine".