51817421 has 2 divisors, whose sum is σ = 51817422. Its totient is φ = 51817420.

The previous prime is 51817391. The next prime is 51817429. The reversal of 51817421 is 12471815.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26677225 + 25140196 = 5165^2 + 5014^2 .

It is a cyclic number.

It is not a de Polignac number, because 51817421 - 2⁶ = 51817357 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51817429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25908710 + 25908711.

It is an arithmetic number, because the mean of its divisors is an integer number (25908711).

Almost surely, 2^51817421 is an apocalyptic number.

It is an amenable number.

51817421 is a deficient number, since it is larger than the sum of its proper divisors (1).

51817421 is an equidigital number, since it uses as much as digits as its factorization.

51817421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2240, while the sum is 29.

The square root of 51817421 is about 7198.4318431169. The cubic root of 51817421 is about 372.8137584374.

The spelling of 51817421 in words is "fifty-one million, eight hundred seventeen thousand, four hundred twenty-one".