123215531 has 4 divisors (see below), whose sum is σ = 128572752. Its totient is φ = 117858312.

The previous prime is 123215509. The next prime is 123215549. The reversal of 123215531 is 135512321.

It is a happy number.

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 123215531 - 2⁶ = 123215467 is a prime.

It is a super-2 number, since 2×123215531² = 30364134159223922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 5357197 = 123215531 / (1 + 2 + 3 + 2 + 1 + 5 + 5 + 3 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 123215497 and 123215506.

It is not an unprimeable number, because it can be changed into a prime (123215581) 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, 2678576 + ... + 2678621.

It is an arithmetic number, because the mean of its divisors is an integer number (32143188).

Almost surely, 2^123215531 is an apocalyptic number.

123215531 is a deficient number, since it is larger than the sum of its proper divisors (5357221).

123215531 is an equidigital number, since it uses as much as digits as its factorization.

123215531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5357220.

The product of its digits is 900, while the sum is 23.

The square root of 123215531 is about 11100.2491413481. The cubic root of 123215531 is about 497.6092952806.

Adding to 123215531 its reverse (135512321), we get a palindrome (258727852).

The spelling of 123215531 in words is "one hundred twenty-three million, two hundred fifteen thousand, five hundred thirty-one".