81630749 has 16 divisors (see below), whose sum is σ = 87744384. Its totient is φ = 75768000.

The previous prime is 81630739. The next prime is 81630763. The reversal of 81630749 is 94703618.

It is a cyclic number.

It is not a de Polignac number, because 81630749 - 2¹² = 81626653 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81630739) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 116099 + ... + 116799.

It is an arithmetic number, because the mean of its divisors is an integer number (5484024).

Almost surely, 2^81630749 is an apocalyptic number.

It is an amenable number.

81630749 is a deficient number, since it is larger than the sum of its proper divisors (6113635).

81630749 is a wasteful number, since it uses less digits than its factorization.

81630749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 868.

The product of its (nonzero) digits is 36288, while the sum is 38.

The square root of 81630749 is about 9034.9736579583. The cubic root of 81630749 is about 433.7950517808.

The spelling of 81630749 in words is "eighty-one million, six hundred thirty thousand, seven hundred forty-nine".