51997381 has 2 divisors, whose sum is σ = 51997382. Its totient is φ = 51997380.

The previous prime is 51997333. The next prime is 51997417. The reversal of 51997381 is 18379915.

51997381 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., 47196900 + 4800481 = 6870^2 + 2191^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51997381 is a prime.

It is a super-2 number, since 2×51997381² = 5407455261718322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51967381) 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, 25998690 + 25998691.

It is an arithmetic number, because the mean of its divisors is an integer number (25998691).

Almost surely, 2^51997381 is an apocalyptic number.

It is an amenable number.

51997381 is a deficient number, since it is larger than the sum of its proper divisors (1).

51997381 is an equidigital number, since it uses as much as digits as its factorization.

51997381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 68040, while the sum is 43.

The square root of 51997381 is about 7210.9209536647. The cubic root of 51997381 is about 373.2448492645.

The spelling of 51997381 in words is "fifty-one million, nine hundred ninety-seven thousand, three hundred eighty-one".