66641666 has 72 divisors (see below), whose sum is σ = 133762356. Its totient is φ = 24675840.

The previous prime is 66641657. The next prime is 66641671. The reversal of 66641666 is 66614666.

It can be written as a sum of positive squares in 6 ways, for example, as 17935225 + 48706441 = 4235^2 + 6979^2 .

It is a super-2 number, since 2×66641666² = 8882223294511112, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 368096 + ... + 368276.

Almost surely, 2^66641666 is an apocalyptic number.

66641666 is an abundant number, since it is smaller than the sum of its proper divisors (67120690).

66641666 is a wasteful number, since it uses less digits than its factorization.

66641666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244 (or 220 counting only the distinct ones).

The product of its digits is 186624, while the sum is 41.

The square root of 66641666 is about 8163.4346938038. The cubic root of 66641666 is about 405.4294403327.

Subtracting from 66641666 its reverse (66614666), we obtain a cube (27000 = 30³).

It can be divided in two parts, 6664 and 1666, that multiplied together give a square (11102224 = 3332²).

The spelling of 66641666 in words is "sixty-six million, six hundred forty-one thousand, six hundred sixty-six".