51415981 has 2 divisors, whose sum is σ = 51415982. Its totient is φ = 51415980.

The previous prime is 51415967. The next prime is 51415993. The reversal of 51415981 is 18951415.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49702500 + 1713481 = 7050^2 + 1309^2 .

It is a cyclic number.

It is not a de Polignac number, because 51415981 - 2¹³ = 51407789 is a prime.

It is a super-2 number, since 2×51415981² = 5287206204384722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51415901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25707990 + 25707991.

It is an arithmetic number, because the mean of its divisors is an integer number (25707991).

Almost surely, 2^51415981 is an apocalyptic number.

It is an amenable number.

51415981 is a deficient number, since it is larger than the sum of its proper divisors (1).

51415981 is an equidigital number, since it uses as much as digits as its factorization.

51415981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7200, while the sum is 34.

The square root of 51415981 is about 7170.4937765819. The cubic root of 51415981 is about 371.8485070315.

The spelling of 51415981 in words is "fifty-one million, four hundred fifteen thousand, nine hundred eighty-one".