51791621 has 4 divisors (see below), whose sum is σ = 59190432. Its totient is φ = 44392812.

The previous prime is 51791611. The next prime is 51791627. The reversal of 51791621 is 12619715.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12619715 = 5 ⋅2523943.

It is a cyclic number.

It is not a de Polignac number, because 51791621 - 2¹⁰ = 51790597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51791627) 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, 3699395 + ... + 3699408.

It is an arithmetic number, because the mean of its divisors is an integer number (14797608).

Almost surely, 2^51791621 is an apocalyptic number.

It is an amenable number.

51791621 is a deficient number, since it is larger than the sum of its proper divisors (7398811).

51791621 is an equidigital number, since it uses as much as digits as its factorization.

51791621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7398810.

The product of its digits is 3780, while the sum is 32.

The square root of 51791621 is about 7196.6395630183. The cubic root of 51791621 is about 372.7518732542.

The spelling of 51791621 in words is "fifty-one million, seven hundred ninety-one thousand, six hundred twenty-one".