81244664 has 8 divisors (see below), whose sum is σ = 152333760. Its totient is φ = 40622328.

The previous prime is 81244663. The next prime is 81244679. The reversal of 81244664 is 46644218.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81244663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5077784 + ... + 5077799.

It is an arithmetic number, because the mean of its divisors is an integer number (19041720).

Almost surely, 2^81244664 is an apocalyptic number.

It is an amenable number.

81244664 is a deficient number, since it is larger than the sum of its proper divisors (71089096).

81244664 is a wasteful number, since it uses less digits than its factorization.

81244664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10155589 (or 10155585 counting only the distinct ones).

The product of its digits is 36864, while the sum is 35.

The square root of 81244664 is about 9013.5821957754. The cubic root of 81244664 is about 433.1100709206.

The spelling of 81244664 in words is "eighty-one million, two hundred forty-four thousand, six hundred sixty-four".