81980617 has 6 divisors (see below), whose sum is σ = 82843998. Its totient is φ = 81126144.

The previous prime is 81980609. The next prime is 81980623. The reversal of 81980617 is 71608918.

It can be written as a sum of positive squares in 3 ways, for example, as 29909961 + 52070656 = 5469^2 + 7216^2 .

It is not a de Polignac number, because 81980617 - 2³ = 81980609 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81980617.

It is not an unprimeable number, because it can be changed into a prime (81980627) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5053 + ... + 13765.

It is an arithmetic number, because the mean of its divisors is an integer number (13807333).

Almost surely, 2^81980617 is an apocalyptic number.

It is an amenable number.

81980617 is a deficient number, since it is larger than the sum of its proper divisors (863381).

81980617 is an frugal number, since it uses more digits than its factorization.

81980617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8907 (or 8810 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 40.

The square root of 81980617 is about 9054.3148277493. The cubic root of 81980617 is about 434.4139145441.

The spelling of 81980617 in words is "eighty-one million, nine hundred eighty thousand, six hundred seventeen".