71643618 has 48 divisors (see below), whose sum is σ = 161211960. Its totient is φ = 22975488.

The previous prime is 71643617. The next prime is 71643619. The reversal of 71643618 is 81634617.

71643618 is a `hidden beast` number, since 7 + 1 + 643 + 6 + 1 + 8 = 666.

It is an interprime number because it is at equal distance from previous prime (71643617) and next prime (71643619).

It can be written as a sum of positive squares in 4 ways, for example, as 53978409 + 17665209 = 7347^2 + 4203^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71643617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 64048 + ... + 65156.

Almost surely, 2^71643618 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 71643618, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80605980).

71643618 is an abundant number, since it is smaller than the sum of its proper divisors (89568342).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

71643618 is a wasteful number, since it uses less digits than its factorization.

71643618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1251 (or 1248 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 71643618 is about 8464.2553127845. The cubic root of 71643618 is about 415.3292360011.

Subtracting 71643618 from its reverse (81634617), we obtain a palindrome (9990999).

The spelling of 71643618 in words is "seventy-one million, six hundred forty-three thousand, six hundred eighteen".