643992129 has 27 divisors (see below), whose sum is σ = 1023794499. Its totient is φ = 389790720.

The previous prime is 643992127. The next prime is 643992131. The reversal of 643992129 is 921299346.

It is a happy number.

The square root of 643992129 is 25377.

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

643992129 is a `hidden beast` number, since 6 + 439 + 92 + 129 = 666.

It is an interprime number because it is at equal distance from previous prime (643992127) and next prime (643992131).

It can be written as a sum of positive squares in only one way, i.e., 251952129 + 392040000 = 15873^2 + 19800^2 .

It is not a de Polignac number, because 643992129 - 2¹ = 643992127 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (643992127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 837057 + ... + 837825.

Almost surely, 2^643992129 is an apocalyptic number.

643992129 is the 25377-th square number.

643992129 is the 12689-th centered octagonal number.

It is an amenable number.

643992129 is a deficient number, since it is larger than the sum of its proper divisors (379802370).

643992129 is an equidigital number, since it uses as much as digits as its factorization.

643992129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1566 (or 783 counting only the distinct ones).

The product of its digits is 209952, while the sum is 45.

The cubic root of 643992129 is about 863.5619926553.

The spelling of 643992129 in words is "six hundred forty-three million, nine hundred ninety-two thousand, one hundred twenty-nine".