51156221 has 4 divisors (see below), whose sum is σ = 51731100. Its totient is φ = 50581344.

The previous prime is 51156181. The next prime is 51156241. The reversal of 51156221 is 12265115.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 35868121 + 15288100 = 5989^2 + 3910^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51156221 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 (51156241) 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, 287306 + ... + 287483.

It is an arithmetic number, because the mean of its divisors is an integer number (12932775).

Almost surely, 2^51156221 is an apocalyptic number.

It is an amenable number.

51156221 is a deficient number, since it is larger than the sum of its proper divisors (574879).

51156221 is an equidigital number, since it uses as much as digits as its factorization.

51156221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 574878.

The product of its digits is 600, while the sum is 23.

The square root of 51156221 is about 7152.3577231567. The cubic root of 51156221 is about 371.2212410316.

The spelling of 51156221 in words is "fifty-one million, one hundred fifty-six thousand, two hundred twenty-one".