399180421 has 2 divisors, whose sum is σ = 399180422. Its totient is φ = 399180420.

The previous prime is 399180409. The next prime is 399180427. The reversal of 399180421 is 124081993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 395612100 + 3568321 = 19890^2 + 1889^2 .

It is a cyclic number.

It is not a de Polignac number, because 399180421 - 2⁷ = 399180293 is a prime.

It is a Chen prime.

It is the 19980-th Hogben number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399180427) by changing a digit.

It is a nontrivial repunit in base 19979.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199590210 + 199590211.

It is an arithmetic number, because the mean of its divisors is an integer number (199590211).

Almost surely, 2^399180421 is an apocalyptic number.

It is an amenable number.

399180421 is a deficient number, since it is larger than the sum of its proper divisors (1).

399180421 is an equidigital number, since it uses as much as digits as its factorization.

399180421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 399180421 is about 19979.5000187692. The cubic root of 399180421 is about 736.3027298333.

The spelling of 399180421 in words is "three hundred ninety-nine million, one hundred eighty thousand, four hundred twenty-one".