66554981 has 2 divisors, whose sum is σ = 66554982. Its totient is φ = 66554980.

The previous prime is 66554977. The next prime is 66554987. The reversal of 66554981 is 18945566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37761025 + 28793956 = 6145^2 + 5366^2 .

It is a cyclic number.

It is not a de Polignac number, because 66554981 - 2² = 66554977 is a prime.

It is a super-2 number, since 2×66554981² = 8859130991820722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66554987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33277490 + 33277491.

It is an arithmetic number, because the mean of its divisors is an integer number (33277491).

Almost surely, 2^66554981 is an apocalyptic number.

It is an amenable number.

66554981 is a deficient number, since it is larger than the sum of its proper divisors (1).

66554981 is an equidigital number, since it uses as much as digits as its factorization.

66554981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 259200, while the sum is 44.

The square root of 66554981 is about 8158.1236200489. The cubic root of 66554981 is about 405.2535748797.

The spelling of 66554981 in words is "sixty-six million, five hundred fifty-four thousand, nine hundred eighty-one".