399661345 has 4 divisors (see below), whose sum is σ = 479593620. Its totient is φ = 319729072.

The previous prime is 399661337. The next prime is 399661357. The reversal of 399661345 is 543166993.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 543166993 = 37 ⋅14680189.

It can be written as a sum of positive squares in 2 ways, for example, as 155176849 + 244484496 = 12457^2 + 15636^2 .

It is a cyclic number.

It is not a de Polignac number, because 399661345 - 2³ = 399661337 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 399661295 and 399661304.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39966130 + ... + 39966139.

It is an arithmetic number, because the mean of its divisors is an integer number (119898405).

Almost surely, 2^399661345 is an apocalyptic number.

It is an amenable number.

399661345 is a deficient number, since it is larger than the sum of its proper divisors (79932275).

399661345 is an equidigital number, since it uses as much as digits as its factorization.

399661345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79932274.

The product of its digits is 524880, while the sum is 46.

The square root of 399661345 is about 19991.5318322534. The cubic root of 399661345 is about 736.5983050705.

It can be divided in two parts, 3996 and 61345, that added together give a triangular number (65341 = T₃₆₁).

The spelling of 399661345 in words is "three hundred ninety-nine million, six hundred sixty-one thousand, three hundred forty-five".