51221231 has 2 divisors, whose sum is σ = 51221232. Its totient is φ = 51221230.

The previous prime is 51221201. The next prime is 51221239. The reversal of 51221231 is 13212215.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 51221231 - 2⁶ = 51221167 is a prime.

It is a super-2 number, since 2×51221231² = 5247229010310722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51221239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25610615 + 25610616.

It is an arithmetic number, because the mean of its divisors is an integer number (25610616).

Almost surely, 2^51221231 is an apocalyptic number.

51221231 is a deficient number, since it is larger than the sum of its proper divisors (1).

51221231 is an equidigital number, since it uses as much as digits as its factorization.

51221231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120, while the sum is 17.

The square root of 51221231 is about 7156.9009354608. The cubic root of 51221231 is about 371.3784254153.

Adding to 51221231 its reverse (13212215), we get a palindrome (64433446).

The spelling of 51221231 in words is "fifty-one million, two hundred twenty-one thousand, two hundred thirty-one".