1631921 has 2 divisors, whose sum is σ = 1631922. Its totient is φ = 1631920.

The previous prime is 1631911. The next prime is 1631939. The reversal of 1631921 is 1291361.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1597696 + 34225 = 1264^2 + 185^2 .

It is a cyclic number.

It is not a de Polignac number, because 1631921 - 2¹⁰ = 1630897 is a prime.

It is not a weakly prime, because it can be changed into another prime (1631911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 815960 + 815961.

It is an arithmetic number, because the mean of its divisors is an integer number (815961).

2^1631921 is an apocalyptic number.

It is an amenable number.

1631921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1631921 is an equidigital number, since it uses as much as digits as its factorization.

1631921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 324, while the sum is 23.

The square root of 1631921 is about 1277.4666336151. The cubic root of 1631921 is about 117.7334065747.

It can be divided in two parts, 1631 and 921, that added together give a palindrome (2552).

The spelling of 1631921 in words is "one million, six hundred thirty-one thousand, nine hundred twenty-one".