51913781 has 2 divisors, whose sum is σ = 51913782. Its totient is φ = 51913780.

The previous prime is 51913753. The next prime is 51913793. The reversal of 51913781 is 18731915.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47748100 + 4165681 = 6910^2 + 2041^2 .

It is a cyclic number.

It is not a de Polignac number, because 51913781 - 2⁶ = 51913717 is a prime.

It is a super-2 number, since 2×51913781² = 5390081315431922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51913711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25956890 + 25956891.

It is an arithmetic number, because the mean of its divisors is an integer number (25956891).

Almost surely, 2^51913781 is an apocalyptic number.

It is an amenable number.

51913781 is a deficient number, since it is larger than the sum of its proper divisors (1).

51913781 is an equidigital number, since it uses as much as digits as its factorization.

51913781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 35.

The square root of 51913781 is about 7205.1218587891. The cubic root of 51913781 is about 373.0447109348.

The spelling of 51913781 in words is "fifty-one million, nine hundred thirteen thousand, seven hundred eighty-one".