66666644 has 36 divisors (see below), whose sum is σ = 129114804. Its totient is φ = 30096000.

The previous prime is 66666643. The next prime is 66666653. The reversal of 66666644 is 44666666.

It can be written as a sum of positive squares in 2 ways, for example, as 407044 + 66259600 = 638^2 + 8140^2 .

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 66666595 and 66666604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66666643) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 87224 + ... + 87984.

Almost surely, 2^66666644 is an apocalyptic number.

It is an amenable number.

66666644 is a deficient number, since it is larger than the sum of its proper divisors (62448160).

66666644 is a wasteful number, since it uses less digits than its factorization.

66666644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 968 (or 955 counting only the distinct ones).

The product of its digits is 746496, while the sum is 44.

The square root of 66666644 is about 8164.9644212330. The cubic root of 66666644 is about 405.4800870838.

66666644 divided by its sum of digits (44) gives a palindrome (1515151).

The spelling of 66666644 in words is "sixty-six million, six hundred sixty-six thousand, six hundred forty-four".