1631 has 4 divisors (see below), whose sum is σ = 1872. Its totient is φ = 1392.

The previous prime is 1627. The next prime is 1637. The reversal of 1631 is 1361.

1631 = T₁₈ + T₁₉ + ... + T₂₄.

1631 is nontrivially palindromic in base 12.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1631 - 2² = 1627 is a prime.

It is a super-2 number, since 2×1631² = 5320322, which contains 22 as substring.

It is a Duffinian number.

1631 is an undulating number in base 12.

It is a nialpdrome in base 13.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 1631.

It is not an unprimeable number, because it can be changed into a prime (1637) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110 + ... + 123.

It is an arithmetic number, because the mean of its divisors is an integer number (468).

2¹⁶³¹ is an apocalyptic number.

1631 is a deficient number, since it is larger than the sum of its proper divisors (241).

1631 is an equidigital number, since it uses as much as digits as its factorization.

1631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240.

The product of its digits is 18, while the sum is 11.

The square root of 1631 is about 40.3856410126. The cubic root of 1631 is about 11.7711254180.

Adding to 1631 its reverse (1361), we get a palindrome (2992).

It can be divided in two parts, 16 and 31, that multiplied together give a triangular number (496 = T₃₁).

The spelling of 1631 in words is "one thousand, six hundred thirty-one".