1631521 has 2 divisors, whose sum is σ = 1631522. Its totient is φ = 1631520.

The previous prime is 1631519. The next prime is 1631537. The reversal of 1631521 is 1251361.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1392400 + 239121 = 1180^2 + 489^2 .

It is a cyclic number.

It is not a de Polignac number, because 1631521 - 2¹ = 1631519 is a prime.

Together with 1631519, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1631821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 815760 + 815761.

It is an arithmetic number, because the mean of its divisors is an integer number (815761).

2^1631521 is an apocalyptic number.

It is an amenable number.

1631521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1631521 is an equidigital number, since it uses as much as digits as its factorization.

1631521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 180, while the sum is 19.

The square root of 1631521 is about 1277.3100641583. The cubic root of 1631521 is about 117.7237865807.

Adding to 1631521 its reverse (1251361), we get a palindrome (2882882).

The spelling of 1631521 in words is "one million, six hundred thirty-one thousand, five hundred twenty-one".