399642493 has 4 divisors (see below), whose sum is σ = 399693888. Its totient is φ = 399591100.

The previous prime is 399642437. The next prime is 399642497. The reversal of 399642493 is 394246993.

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 399642493 - 2⁹ = 399641981 is a prime.

It is a super-2 number, since 2×399642493² = 319428244422510098, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399642497) 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, 11371 + ... + 30472.

It is an arithmetic number, because the mean of its divisors is an integer number (99923472).

Almost surely, 2^399642493 is an apocalyptic number.

It is an amenable number.

399642493 is a deficient number, since it is larger than the sum of its proper divisors (51395).

399642493 is an equidigital number, since it uses as much as digits as its factorization.

399642493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51394.

The product of its digits is 1259712, while the sum is 49.

The square root of 399642493 is about 19991.0603270562. The cubic root of 399642493 is about 736.5867231234.

The spelling of 399642493 in words is "three hundred ninety-nine million, six hundred forty-two thousand, four hundred ninety-three".