51931661 has 4 divisors (see below), whose sum is σ = 51948924. Its totient is φ = 51914400.

The previous prime is 51931657. The next prime is 51931667. The reversal of 51931661 is 16613915.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16613915 = 5 ⋅3322783.

It can be written as a sum of positive squares in 2 ways, for example, as 18361225 + 33570436 = 4285^2 + 5794^2 .

It is a cyclic number.

It is not a de Polignac number, because 51931661 - 2² = 51931657 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 (51931667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2810 + ... + 10571.

It is an arithmetic number, because the mean of its divisors is an integer number (12987231).

Almost surely, 2^51931661 is an apocalyptic number.

It is an amenable number.

51931661 is a deficient number, since it is larger than the sum of its proper divisors (17263).

51931661 is a wasteful number, since it uses less digits than its factorization.

51931661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17262.

The product of its digits is 4860, while the sum is 32.

The square root of 51931661 is about 7206.3625359817. The cubic root of 51931661 is about 373.0875336927.

The spelling of 51931661 in words is "fifty-one million, nine hundred thirty-one thousand, six hundred sixty-one".