1213531 has 4 divisors (see below), whose sum is σ = 1323864. Its totient is φ = 1103200.

The previous prime is 1213529. The next prime is 1213547. The reversal of 1213531 is 1353121.

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 1213531 - 2¹ = 1213529 is a prime.

It is a super-2 number, since 2×1213531² = 2945314975922, which contains 22 as substring.

It is a Duffinian number.

1213531 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1213561) 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, 55150 + ... + 55171.

It is an arithmetic number, because the mean of its divisors is an integer number (330966).

2^1213531 is an apocalyptic number.

1213531 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1213531 is a deficient number, since it is larger than the sum of its proper divisors (110333).

1213531 is a wasteful number, since it uses less digits than its factorization.

1213531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110332.

The product of its digits is 90, while the sum is 16.

The square root of 1213531 is about 1101.6038307849. The cubic root of 1213531 is about 106.6637770485.

Adding to 1213531 its reverse (1353121), we get a palindrome (2566652).

The spelling of 1213531 in words is "one million, two hundred thirteen thousand, five hundred thirty-one".