643992701 has 4 divisors (see below), whose sum is σ = 702537504. Its totient is φ = 585447900.

The previous prime is 643992689. The next prime is 643992703. The reversal of 643992701 is 107299346.

643992701 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 643992701 - 2¹⁴ = 643976317 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643992703) 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, 29272385 + ... + 29272406.

It is an arithmetic number, because the mean of its divisors is an integer number (175634376).

Almost surely, 2^643992701 is an apocalyptic number.

It is an amenable number.

643992701 is a deficient number, since it is larger than the sum of its proper divisors (58544803).

643992701 is a wasteful number, since it uses less digits than its factorization.

643992701 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58544802.

The product of its (nonzero) digits is 81648, while the sum is 41.

The square root of 643992701 is about 25377.0112700452. The cubic root of 643992701 is about 863.5622483299.

The spelling of 643992701 in words is "six hundred forty-three million, nine hundred ninety-two thousand, seven hundred one".