51645421 has 2 divisors, whose sum is σ = 51645422. Its totient is φ = 51645420.

The previous prime is 51645413. The next prime is 51645427. The reversal of 51645421 is 12454615.

51645421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49196196 + 2449225 = 7014^2 + 1565^2 .

It is a cyclic number.

It is not a de Polignac number, because 51645421 - 2³ = 51645413 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 51645421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51645427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25822710 + 25822711.

It is an arithmetic number, because the mean of its divisors is an integer number (25822711).

Almost surely, 2^51645421 is an apocalyptic number.

It is an amenable number.

51645421 is a deficient number, since it is larger than the sum of its proper divisors (1).

51645421 is an equidigital number, since it uses as much as digits as its factorization.

51645421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4800, while the sum is 28.

The square root of 51645421 is about 7186.4748660244. The cubic root of 51645421 is about 372.4008017764.

It can be divided in two parts, 5164 and 5421, that added together give a triangular number (10585 = T₁₄₅).

The spelling of 51645421 in words is "fifty-one million, six hundred forty-five thousand, four hundred twenty-one".