646328929 has 3 divisors (see below), whose sum is σ = 646354353. Its totient is φ = 646303506.

The previous prime is 646328927. The next prime is 646328971. The reversal of 646328929 is 929823646.

It is a happy number.

The square root of 646328929 is 25423.

It is a perfect power (a square), and thus also a powerful number.

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: 929823646 = 2 ⋅464911823.

It is not a de Polignac number, because 646328929 - 2¹ = 646328927 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646328927) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 12712 + ... + 38134.

It is an arithmetic number, because the mean of its divisors is an integer number (215451451).

Almost surely, 2^646328929 is an apocalyptic number.

646328929 is the 25423-rd square number.

646328929 is the 12712-nd centered octagonal number.

It is an amenable number.

646328929 is a deficient number, since it is larger than the sum of its proper divisors (25424).

646328929 is an frugal number, since it uses more digits than its factorization.

646328929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50846 (or 25423 counting only the distinct ones).

The product of its digits is 1119744, while the sum is 49.

The cubic root of 646328929 is about 864.6052433762.

Multiplying 646328929 by its sum of digits (49), we get a square (31670117521 = 177961²).

The spelling of 646328929 in words is "six hundred forty-six million, three hundred twenty-eight thousand, nine hundred twenty-nine".