1531 has 2 divisors, whose sum is σ = 1532. Its totient is φ = 1530.

The previous prime is 1523. The next prime is 1543. The reversal of 1531 is 1351.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1531 - 2³ = 1523 is a prime.

It is a super-2 number, since 2×1531² = 4687922, which contains 22 as substring.

It is an Ulam number.

It is a nialpdrome in base 5 and base 12.

It is a zygodrome in base 5.

It is not a weakly prime, because it can be changed into another prime (1511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 765 + 766.

It is an arithmetic number, because the mean of its divisors is an integer number (766).

1531 is the 18-th centered decagonal number.

1531 is a deficient number, since it is larger than the sum of its proper divisors (1).

1531 is an equidigital number, since it uses as much as digits as its factorization.

1531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15, while the sum is 10.

The square root of 1531 is about 39.1279950930. The cubic root of 1531 is about 11.5254634258.

Subtracting from 1531 its sum of digits (10), we obtain a square (1521 = 39²).

Adding to 1531 its reverse (1351), we get a palindrome (2882).

It can be divided in two parts, 15 and 31, that multiplied together give a triangular number (465 = T₃₀).

The spelling of 1531 in words is "one thousand, five hundred thirty-one".