396931921 has 2 divisors, whose sum is σ = 396931922. Its totient is φ = 396931920.

The previous prime is 396931897. The next prime is 396931933. The reversal of 396931921 is 129139693.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 377913600 + 19018321 = 19440^2 + 4361^2 .

It is an emirp because it is prime and its reverse (129139693) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 396931921 - 2¹⁷ = 396800849 is a prime.

It is not a weakly prime, because it can be changed into another prime (396931981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 198465960 + 198465961.

It is an arithmetic number, because the mean of its divisors is an integer number (198465961).

Almost surely, 2^396931921 is an apocalyptic number.

It is an amenable number.

396931921 is a deficient number, since it is larger than the sum of its proper divisors (1).

396931921 is an equidigital number, since it uses as much as digits as its factorization.

396931921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 78732, while the sum is 43.

The square root of 396931921 is about 19923.1503783915. The cubic root of 396931921 is about 734.9176460708.

It can be divided in two parts, 39693 and 1921, that added together give a palindrome (41614).

The spelling of 396931921 in words is "three hundred ninety-six million, nine hundred thirty-one thousand, nine hundred twenty-one".