1243213531 has 4 divisors (see below), whose sum is σ = 1420815472. Its totient is φ = 1065611592.

The previous prime is 1243213513. The next prime is 1243213547. The reversal of 1243213531 is 1353123421.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1353123421 = 13 ⋅104086417.

It is a cyclic number.

It is not a de Polignac number, because 1243213531 - 2⁹ = 1243213019 is a prime.

It is a super-2 number, since 2×1243213531² = 3091159767322975922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1243213496 and 1243213505.

It is not an unprimeable number, because it can be changed into a prime (1243213571) 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, 88800960 + ... + 88800973.

It is an arithmetic number, because the mean of its divisors is an integer number (355203868).

Almost surely, 2^1243213531 is an apocalyptic number.

1243213531 is a deficient number, since it is larger than the sum of its proper divisors (177601941).

1243213531 is an equidigital number, since it uses as much as digits as its factorization.

1243213531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177601940.

The product of its digits is 2160, while the sum is 25.

The square root of 1243213531 is about 35259.2332730024. The cubic root of 1243213531 is about 1075.2643391049.

Adding to 1243213531 its reverse (1353123421), we get a palindrome (2596336952).

The spelling of 1243213531 in words is "one billion, two hundred forty-three million, two hundred thirteen thousand, five hundred thirty-one".