399999971 has 4 divisors (see below), whose sum is σ = 457142832. Its totient is φ = 342857112.

The previous prime is 399999959. The next prime is 400000009. The reversal of 399999971 is 179999993.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 399999971 - 2⁶ = 399999907 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 399999898 and 399999907.

It is not an unprimeable number, because it can be changed into a prime (399999931) 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, 28571420 + ... + 28571433.

It is an arithmetic number, because the mean of its divisors is an integer number (114285708).

Almost surely, 2^399999971 is an apocalyptic number.

399999971 is a deficient number, since it is larger than the sum of its proper divisors (57142861).

399999971 is an equidigital number, since it uses as much as digits as its factorization.

399999971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57142860.

The product of its digits is 11160261, while the sum is 65.

The square root of 399999971 is about 19999.9992750000. Note that the first 3 decimals coincide. The cubic root of 399999971 is about 736.8062819219.

The spelling of 399999971 in words is "three hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred seventy-one".