51221031505251 has 4 divisors (see below), whose sum is σ = 68294708673672. Its totient is φ = 34147354336832.

The previous prime is 51221031505223. The next prime is 51221031505277. The reversal of 51221031505251 is 15250513012215.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 51221031505251 - 2¹⁷ = 51221031374179 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51221031505201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8536838584206 + ... + 8536838584211.

It is an arithmetic number, because the mean of its divisors is an integer number (17073677168418).

Almost surely, 2^{51221031505251} is an apocalyptic number.

51221031505251 is a deficient number, since it is larger than the sum of its proper divisors (17073677168421).

51221031505251 is a wasteful number, since it uses less digits than its factorization.

51221031505251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17073677168420.

The product of its (nonzero) digits is 15000, while the sum is 33.

Adding to 51221031505251 its reverse (15250513012215), we get a palindrome (66471544517466).

The spelling of 51221031505251 in words is "fifty-one trillion, two hundred twenty-one billion, thirty-one million, five hundred five thousand, two hundred fifty-one".