221213437 has 2 divisors, whose sum is σ = 221213438. Its totient is φ = 221213436.

The previous prime is 221213413. The next prime is 221213441. The reversal of 221213437 is 734312122.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 202037796 + 19175641 = 14214^2 + 4379^2 .

It is a cyclic number.

It is not a de Polignac number, because 221213437 - 2⁷ = 221213309 is a prime.

It is a super-3 number, since 3×221213437³ (a number of 26 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221213407) 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, 110606718 + 110606719.

It is an arithmetic number, because the mean of its divisors is an integer number (110606719).

Almost surely, 2^221213437 is an apocalyptic number.

It is an amenable number.

221213437 is a deficient number, since it is larger than the sum of its proper divisors (1).

221213437 is an equidigital number, since it uses as much as digits as its factorization.

221213437 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 25.

The square root of 221213437 is about 14873.2456780623. The cubic root of 221213437 is about 604.7889316772.

Adding to 221213437 its reverse (734312122), we get a palindrome (955525559).

The spelling of 221213437 in words is "two hundred twenty-one million, two hundred thirteen thousand, four hundred thirty-seven".