51128202817221 has 4 divisors (see below), whose sum is σ = 68170937089632. Its totient is φ = 34085468544812.

The previous prime is 51128202817193. The next prime is 51128202817261. The reversal of 51128202817221 is 12271820282115.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 51128202817221 - 2¹⁴ = 51128202800837 is a prime.

It is a super-2 number, since 2×51128202817221² (a number of 28 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51128202817261) 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, 8521367136201 + ... + 8521367136206.

It is an arithmetic number, because the mean of its divisors is an integer number (17042734272408).

Almost surely, 2^{51128202817221} is an apocalyptic number.

It is an amenable number.

51128202817221 is a deficient number, since it is larger than the sum of its proper divisors (17042734272411).

51128202817221 is a wasteful number, since it uses less digits than its factorization.

51128202817221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17042734272410.

The product of its (nonzero) digits is 71680, while the sum is 42.

The spelling of 51128202817221 in words is "fifty-one trillion, one hundred twenty-eight billion, two hundred two million, eight hundred seventeen thousand, two hundred twenty-one".