66283781 has 4 divisors (see below), whose sum is σ = 67191852. Its totient is φ = 65375712.

The previous prime is 66283733. The next prime is 66283783. The reversal of 66283781 is 18738266.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 53787556 + 12496225 = 7334^2 + 3535^2 .

It is a cyclic number.

It is not a de Polignac number, because 66283781 - 2²² = 62089477 is a prime.

It is a super-2 number, since 2×66283781² = 8787079247311922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66283783) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 453926 + ... + 454071.

It is an arithmetic number, because the mean of its divisors is an integer number (16797963).

Almost surely, 2^66283781 is an apocalyptic number.

It is an amenable number.

66283781 is a deficient number, since it is larger than the sum of its proper divisors (908071).

66283781 is an equidigital number, since it uses as much as digits as its factorization.

66283781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 908070.

The product of its digits is 96768, while the sum is 41.

The square root of 66283781 is about 8141.4851839207. The cubic root of 66283781 is about 404.7023795238.

The spelling of 66283781 in words is "sixty-six million, two hundred eighty-three thousand, seven hundred eighty-one".