1531631 has 2 divisors, whose sum is σ = 1531632. Its totient is φ = 1531630.

The previous prime is 1531627. The next prime is 1531633. The reversal of 1531631 is 1361351.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1531631 - 2² = 1531627 is a prime.

It is a super-2 number, since 2×1531631² = 4691787040322, which contains 22 as substring.

Together with 1531633, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1531633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 765815 + 765816.

It is an arithmetic number, because the mean of its divisors is an integer number (765816).

2^1531631 is an apocalyptic number.

1531631 is a deficient number, since it is larger than the sum of its proper divisors (1).

1531631 is an equidigital number, since it uses as much as digits as its factorization.

1531631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 270, while the sum is 20.

The square root of 1531631 is about 1237.5908047493. The cubic root of 1531631 is about 115.2704661072.

Adding to 1531631 its reverse (1361351), we get a palindrome (2892982).

The spelling of 1531631 in words is "one million, five hundred thirty-one thousand, six hundred thirty-one".