51547781 has 2 divisors, whose sum is σ = 51547782. Its totient is φ = 51547780.

The previous prime is 51547777. The next prime is 51547787. The reversal of 51547781 is 18774515.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 39262756 + 12285025 = 6266^2 + 3505^2 .

It is a cyclic number.

It is not a de Polignac number, because 51547781 - 2² = 51547777 is a prime.

It is a super-2 number, since 2×51547781² = 5314347452047922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51547787) 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 as a sum of consecutive naturals, namely, 25773890 + 25773891.

It is an arithmetic number, because the mean of its divisors is an integer number (25773891).

Almost surely, 2^51547781 is an apocalyptic number.

It is an amenable number.

51547781 is a deficient number, since it is larger than the sum of its proper divisors (1).

51547781 is an equidigital number, since it uses as much as digits as its factorization.

51547781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 39200, while the sum is 38.

The square root of 51547781 is about 7179.6783354131. The cubic root of 51547781 is about 372.1659687404.

The spelling of 51547781 in words is "fifty-one million, five hundred forty-seven thousand, seven hundred eighty-one".