81759644 has 6 divisors (see below), whose sum is σ = 143079384. Its totient is φ = 40879820.

The previous prime is 81759611. The next prime is 81759683. The reversal of 81759644 is 44695718.

It is a junction number, because it is equal to n+sod(n) for n = 81759595 and 81759604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10219952 + ... + 10219959.

It is an arithmetic number, because the mean of its divisors is an integer number (23846564).

Almost surely, 2^81759644 is an apocalyptic number.

It is an amenable number.

81759644 is a deficient number, since it is larger than the sum of its proper divisors (61319740).

81759644 is a wasteful number, since it uses less digits than its factorization.

81759644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20439915 (or 20439913 counting only the distinct ones).

The product of its digits is 241920, while the sum is 44.

The square root of 81759644 is about 9042.1039587034. The cubic root of 81759644 is about 434.0232525926.

The spelling of 81759644 in words is "eighty-one million, seven hundred fifty-nine thousand, six hundred forty-four".