66777664 has 14 divisors (see below), whose sum is σ = 132512054. Its totient is φ = 33388800.

The previous prime is 66777661. The next prime is 66777703. The reversal of 66777664 is 46677766.

It can be written as a sum of positive squares in only one way, i.e., 58982400 + 7795264 = 7680^2 + 2792^2 .

It is a super-3 number, since 3×66777664³ (a number of 24 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (66777661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 521637 + ... + 521764.

Almost surely, 2^66777664 is an apocalyptic number.

66777664 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

66777664 is a deficient number, since it is larger than the sum of its proper divisors (65734390).

66777664 is a wasteful number, since it uses less digits than its factorization.

66777664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1043413 (or 1043403 counting only the distinct ones).

The product of its digits is 1778112, while the sum is 49.

The square root of 66777664 is about 8171.7601531127. The cubic root of 66777664 is about 405.7050443290.

It can be divided in two parts, 6677 and 7664, that added together give a palindrome (14341).

The spelling of 66777664 in words is "sixty-six million, seven hundred seventy-seven thousand, six hundred sixty-four".