399720643 has 8 divisors (see below), whose sum is σ = 483695712. Its totient is φ = 322463616.

The previous prime is 399720637. The next prime is 399720667. The reversal of 399720643 is 346027993.

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

It is not a de Polignac number, because 399720643 - 2¹³ = 399712451 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 399720643.

It is not an unprimeable number, because it can be changed into a prime (399720743) 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, 1679380 + ... + 1679617.

It is an arithmetic number, because the mean of its divisors is an integer number (60461964).

Almost surely, 2^399720643 is an apocalyptic number.

399720643 is a deficient number, since it is larger than the sum of its proper divisors (83975069).

399720643 is a wasteful number, since it uses less digits than its factorization.

399720643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3359021.

The product of its (nonzero) digits is 244944, while the sum is 43.

The square root of 399720643 is about 19993.0148551938. The cubic root of 399720643 is about 736.6347331170.

The spelling of 399720643 in words is "three hundred ninety-nine million, seven hundred twenty thousand, six hundred forty-three".