51323721 has 4 divisors (see below), whose sum is σ = 68431632. Its totient is φ = 34215812.

The previous prime is 51323711. The next prime is 51323743. The reversal of 51323721 is 12732315.

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 51323721 - 2⁷ = 51323593 is a prime.

It is a super-4 number, since 4×51323721⁴ (a number of 32 digits) contains 4444 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 51323691 and 51323700.

It is not an unprimeable number, because it can be changed into a prime (51323711) 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, 8553951 + ... + 8553956.

It is an arithmetic number, because the mean of its divisors is an integer number (17107908).

Almost surely, 2^51323721 is an apocalyptic number.

It is an amenable number.

51323721 is a deficient number, since it is larger than the sum of its proper divisors (17107911).

51323721 is a wasteful number, since it uses less digits than its factorization.

51323721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17107910.

The product of its digits is 1260, while the sum is 24.

The square root of 51323721 is about 7164.0575793331. The cubic root of 51323721 is about 371.6259608964.

The spelling of 51323721 in words is "fifty-one million, three hundred twenty-three thousand, seven hundred twenty-one".