81720947395 has 8 divisors (see below), whose sum is σ = 98066691504. Its totient is φ = 65375721504.

The previous prime is 81720947381. The next prime is 81720947417. The reversal of 81720947395 is 59374902718.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81720947395 - 2⁹ = 81720946883 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 467677 + ... + 618193.

It is an arithmetic number, because the mean of its divisors is an integer number (12258336438).

Almost surely, 2^81720947395 is an apocalyptic number.

81720947395 is a deficient number, since it is larger than the sum of its proper divisors (16345744109).

81720947395 is a wasteful number, since it uses less digits than its factorization.

81720947395 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259109.

The product of its (nonzero) digits is 3810240, while the sum is 55.

The spelling of 81720947395 in words is "eighty-one billion, seven hundred twenty million, nine hundred forty-seven thousand, three hundred ninety-five".