66116381 has 2 divisors, whose sum is σ = 66116382. Its totient is φ = 66116380.

The previous prime is 66116363. The next prime is 66116429. The reversal of 66116381 is 18361166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 40208281 + 25908100 = 6341^2 + 5090^2 .

It is a cyclic number.

It is not a de Polignac number, because 66116381 - 2¹⁴ = 66099997 is a prime.

It is a super-2 number, since 2×66116381² = 8742751673074322, 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 (66116321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33058190 + 33058191.

It is an arithmetic number, because the mean of its divisors is an integer number (33058191).

Almost surely, 2^66116381 is an apocalyptic number.

It is an amenable number.

66116381 is a deficient number, since it is larger than the sum of its proper divisors (1).

66116381 is an equidigital number, since it uses as much as digits as its factorization.

66116381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 32.

The square root of 66116381 is about 8131.1980052142. The cubic root of 66116381 is about 404.3613997275.

The spelling of 66116381 in words is "sixty-six million, one hundred sixteen thousand, three hundred eighty-one".