221212531 has 2 divisors, whose sum is σ = 221212532. Its totient is φ = 221212530.

The previous prime is 221212501. The next prime is 221212543. The reversal of 221212531 is 135212122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221212531 - 2¹³ = 221204339 is a prime.

It is a super-2 number, since 2×221212531² = 97869967742851922, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 221212499 and 221212508.

It is not a weakly prime, because it can be changed into another prime (221212501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110606265 + 110606266.

It is an arithmetic number, because the mean of its divisors is an integer number (110606266).

Almost surely, 2^221212531 is an apocalyptic number.

221212531 is a deficient number, since it is larger than the sum of its proper divisors (1).

221212531 is an equidigital number, since it uses as much as digits as its factorization.

221212531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 240, while the sum is 19.

The square root of 221212531 is about 14873.2152206576. The cubic root of 221212531 is about 604.7881060198.

Adding to 221212531 its reverse (135212122), we get a palindrome (356424653).

The spelling of 221212531 in words is "two hundred twenty-one million, two hundred twelve thousand, five hundred thirty-one".