66881761 has 2 divisors, whose sum is σ = 66881762. Its totient is φ = 66881760.

The previous prime is 66881747. The next prime is 66881777. The reversal of 66881761 is 16718866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57153600 + 9728161 = 7560^2 + 3119^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66881761 is a prime.

It is a super-2 number, since 2×66881761² = 8946339908922242, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (66881261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33440880 + 33440881.

It is an arithmetic number, because the mean of its divisors is an integer number (33440881).

Almost surely, 2^66881761 is an apocalyptic number.

It is an amenable number.

66881761 is a deficient number, since it is larger than the sum of its proper divisors (1).

66881761 is an equidigital number, since it uses as much as digits as its factorization.

66881761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96768, while the sum is 43.

The square root of 66881761 is about 8178.1269860525. The cubic root of 66881761 is about 405.9157472773.

The spelling of 66881761 in words is "sixty-six million, eight hundred eighty-one thousand, seven hundred sixty-one".