212115531 has 4 divisors (see below), whose sum is σ = 282820712. Its totient is φ = 141410352.

The previous prime is 212115523. The next prime is 212115539. The reversal of 212115531 is 135511212.

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

It is an interprime number because it is at equal distance from previous prime (212115523) and next prime (212115539).

It is not a de Polignac number, because 212115531 - 2³ = 212115523 is a prime.

It is a super-2 number, since 2×212115531² = 89985996982823922, 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 = 212115498 and 212115507.

It is not an unprimeable number, because it can be changed into a prime (212115539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35352586 + ... + 35352591.

It is an arithmetic number, because the mean of its divisors is an integer number (70705178).

Almost surely, 2^212115531 is an apocalyptic number.

212115531 is a deficient number, since it is larger than the sum of its proper divisors (70705181).

212115531 is an equidigital number, since it uses as much as digits as its factorization.

212115531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70705180.

The product of its digits is 300, while the sum is 21.

The square root of 212115531 is about 14564.1865890272. The cubic root of 212115531 is about 596.3814906308.

Adding to 212115531 its reverse (135511212), we get a palindrome (347626743).

The spelling of 212115531 in words is "two hundred twelve million, one hundred fifteen thousand, five hundred thirty-one".