51431221 has 8 divisors (see below), whose sum is σ = 53001944. Its totient is φ = 49870080.

The previous prime is 51431213. The next prime is 51431249. The reversal of 51431221 is 12213415.

It can be written as a sum of positive squares in 4 ways, for example, as 2235025 + 49196196 = 1495^2 + 7014^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 51431221 - 2³ = 51431213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51431021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9361 + ... + 13801.

It is an arithmetic number, because the mean of its divisors is an integer number (6625243).

Almost surely, 2^51431221 is an apocalyptic number.

51431221 is the 4141-st hex number.

It is an amenable number.

51431221 is a deficient number, since it is larger than the sum of its proper divisors (1570723).

51431221 is a wasteful number, since it uses less digits than its factorization.

51431221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4791.

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

The square root of 51431221 is about 7171.5563861689. The cubic root of 51431221 is about 371.8852427657.

Adding to 51431221 its reverse (12213415), we get a palindrome (63644636).

The spelling of 51431221 in words is "fifty-one million, four hundred thirty-one thousand, two hundred twenty-one".