1218531 has 4 divisors (see below), whose sum is σ = 1624712. Its totient is φ = 812352.

The previous prime is 1218487. The next prime is 1218533. The reversal of 1218531 is 1358121.

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

It is not a de Polignac number, because 1218531 - 2⁶ = 1218467 is a prime.

It is a super-2 number, since 2×1218531² = 2969635595922, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1218498 and 1218507.

It is not an unprimeable number, because it can be changed into a prime (1218533) 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, 203086 + ... + 203091.

It is an arithmetic number, because the mean of its divisors is an integer number (406178).

2^1218531 is an apocalyptic number.

1218531 is a deficient number, since it is larger than the sum of its proper divisors (406181).

1218531 is an equidigital number, since it uses as much as digits as its factorization.

1218531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406180.

The product of its digits is 240, while the sum is 21.

The square root of 1218531 is about 1103.8709163666. The cubic root of 1218531 is about 106.8100686267.

The spelling of 1218531 in words is "one million, two hundred eighteen thousand, five hundred thirty-one".