212421531 has 16 divisors (see below), whose sum is σ = 324126464. Its totient is φ = 121220064.

The previous prime is 212421523. The next prime is 212421569. The reversal of 212421531 is 135124212.

It is not a de Polignac number, because 212421531 - 2³ = 212421523 is a prime.

It is a super-2 number, since 2×212421531² = 90245813664767922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 212421498 and 212421507.

It is not an unprimeable number, because it can be changed into a prime (212421431) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10101 + ... + 22953.

It is an arithmetic number, because the mean of its divisors is an integer number (20257904).

Almost surely, 2^212421531 is an apocalyptic number.

212421531 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

212421531 is a deficient number, since it is larger than the sum of its proper divisors (111704933).

212421531 is a wasteful number, since it uses less digits than its factorization.

212421531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13650.

The product of its digits is 480, while the sum is 21.

The square root of 212421531 is about 14574.6880241054. The cubic root of 212421531 is about 596.6681348167.

Adding to 212421531 its reverse (135124212), we get a palindrome (347545743).

The spelling of 212421531 in words is "two hundred twelve million, four hundred twenty-one thousand, five hundred thirty-one".