643123861 has 8 divisors (see below), whose sum is σ = 692734464. Its totient is φ = 595317360.

The previous prime is 643123849. The next prime is 643123883. The reversal of 643123861 is 168321346.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643123861 - 2¹⁷ = 642992789 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 (643123801) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 450286 + ... + 451711.

It is an arithmetic number, because the mean of its divisors is an integer number (86591808).

Almost surely, 2^643123861 is an apocalyptic number.

It is an amenable number.

643123861 is a deficient number, since it is larger than the sum of its proper divisors (49610603).

643123861 is a wasteful number, since it uses less digits than its factorization.

643123861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 902051.

The product of its digits is 20736, while the sum is 34.

The square root of 643123861 is about 25359.8868491167. The cubic root of 643123861 is about 863.1737164434.

The spelling of 643123861 in words is "six hundred forty-three million, one hundred twenty-three thousand, eight hundred sixty-one".