66818631049 has 9 divisors (see below), whose sum is σ = 67765630869. Its totient is φ = 65884695840.

The previous prime is 66818631043. The next prime is 66818631059. The reversal of 66818631049 is 94013681866.

The square root of 66818631049 is 258493.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 12924025 + 66805707024 = 3595^2 + 258468^2 .

It is not a de Polignac number, because 66818631049 - 2⁵ = 66818631017 is a prime.

It is a super-3 number, since 3×66818631049³ (a number of 33 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66818630987 and 66818631005.

It is not an unprimeable number, because it can be changed into a prime (66818631043) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 18868219 + ... + 18871759.

It is an arithmetic number, because the mean of its divisors is an integer number (7529514541).

Almost surely, 2^66818631049 is an apocalyptic number.

66818631049 is the 258493-rd square number.

66818631049 is the 129247-th centered octagonal number.

It is an amenable number.

66818631049 is a deficient number, since it is larger than the sum of its proper divisors (946999820).

66818631049 is an frugal number, since it uses more digits than its factorization.

66818631049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7228 (or 3614 counting only the distinct ones).

The product of its (nonzero) digits is 1492992, while the sum is 52.

The spelling of 66818631049 in words is "sixty-six billion, eight hundred eighteen million, six hundred thirty-one thousand, forty-nine".