399201421 has 2 divisors, whose sum is σ = 399201422. Its totient is φ = 399201420.

The previous prime is 399201377. The next prime is 399201433. The reversal of 399201421 is 124102993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 307616521 + 91584900 = 17539^2 + 9570^2 .

It is a cyclic number.

It is not a de Polignac number, because 399201421 - 2¹³ = 399193229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399201521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199600710 + 199600711.

It is an arithmetic number, because the mean of its divisors is an integer number (199600711).

Almost surely, 2^399201421 is an apocalyptic number.

It is an amenable number.

399201421 is a deficient number, since it is larger than the sum of its proper divisors (1).

399201421 is an equidigital number, since it uses as much as digits as its factorization.

399201421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 399201421 is about 19980.0255505342. The cubic root of 399201421 is about 736.3156413602.

The spelling of 399201421 in words is "three hundred ninety-nine million, two hundred one thousand, four hundred twenty-one".