51645921 has 4 divisors (see below), whose sum is σ = 68861232. Its totient is φ = 34430612.

The previous prime is 51645911. The next prime is 51645931. The reversal of 51645921 is 12954615.

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 an interprime number because it is at equal distance from previous prime (51645911) and next prime (51645931).

It is a cyclic number.

It is not a de Polignac number, because 51645921 - 2⁵ = 51645889 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51645911) 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, 8607651 + ... + 8607656.

It is an arithmetic number, because the mean of its divisors is an integer number (17215308).

Almost surely, 2^51645921 is an apocalyptic number.

It is an amenable number.

51645921 is a deficient number, since it is larger than the sum of its proper divisors (17215311).

51645921 is a wasteful number, since it uses less digits than its factorization.

51645921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17215310.

The product of its digits is 10800, while the sum is 33.

The square root of 51645921 is about 7186.5096535105. The cubic root of 51645921 is about 372.4020035596.

The spelling of 51645921 in words is "fifty-one million, six hundred forty-five thousand, nine hundred twenty-one".