51661321 has 4 divisors (see below), whose sum is σ = 51990532. Its totient is φ = 51332112.

The previous prime is 51661307. The next prime is 51661333. The reversal of 51661321 is 12316615.

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 28515600 + 23145721 = 5340^2 + 4811^2 .

It is a cyclic number.

It is not a de Polignac number, because 51661321 - 2¹¹ = 51659273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51661391) 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, 164370 + ... + 164683.

It is an arithmetic number, because the mean of its divisors is an integer number (12997633).

Almost surely, 2^51661321 is an apocalyptic number.

It is an amenable number.

51661321 is a deficient number, since it is larger than the sum of its proper divisors (329211).

51661321 is a wasteful number, since it uses less digits than its factorization.

51661321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329210.

The product of its digits is 1080, while the sum is 25.

The square root of 51661321 is about 7187.5810256303. The cubic root of 51661321 is about 372.4390146847.

Adding to 51661321 its reverse (12316615), we get a palindrome (63977936).

It can be divided in two parts, 5166 and 1321, that multiplied together give a palindrome (6824286).

The spelling of 51661321 in words is "fifty-one million, six hundred sixty-one thousand, three hundred twenty-one".