51540331221 has 12 divisors (see below), whose sum is σ = 74528165920. Its totient is φ = 34322826600.

The previous prime is 51540331217. The next prime is 51540331231. The reversal of 51540331221 is 12213304515.

51540331221 is a `hidden beast` number, since 5 + 1 + 5 + 403 + 31 + 221 = 666.

It is not a de Polignac number, because 51540331221 - 2² = 51540331217 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 (51540331201) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3107455 + ... + 3123996.

Almost surely, 2^51540331221 is an apocalyptic number.

It is an amenable number.

51540331221 is a deficient number, since it is larger than the sum of its proper divisors (22987834699).

51540331221 is a wasteful number, since it uses less digits than its factorization.

51540331221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6232376 (or 6232373 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

Adding to 51540331221 its reverse (12213304515), we get a palindrome (63753635736).

The spelling of 51540331221 in words is "fifty-one billion, five hundred forty million, three hundred thirty-one thousand, two hundred twenty-one".