66447881 has 2 divisors, whose sum is σ = 66447882. Its totient is φ = 66447880.

The previous prime is 66447869. The next prime is 66447889. The reversal of 66447881 is 18874466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53523856 + 12924025 = 7316^2 + 3595^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66447881 is a prime.

It is a super-2 number, since 2×66447881² = 8830641778780322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (66447889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33223940 + 33223941.

It is an arithmetic number, because the mean of its divisors is an integer number (33223941).

Almost surely, 2^66447881 is an apocalyptic number.

It is an amenable number.

66447881 is a deficient number, since it is larger than the sum of its proper divisors (1).

66447881 is an equidigital number, since it uses as much as digits as its factorization.

66447881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 258048, while the sum is 44.

The square root of 66447881 is about 8151.5569678436. The cubic root of 66447881 is about 405.0360807158.

The spelling of 66447881 in words is "sixty-six million, four hundred forty-seven thousand, eight hundred eighty-one".