81747450581 has 8 divisors (see below), whose sum is σ = 86321405280. Its totient is φ = 77200641648.

The previous prime is 81747450559. The next prime is 81747450611. The reversal of 81747450581 is 18505474718.

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 81747450581 - 2³⁰ = 80673708757 is a prime.

It is a super-2 number, since 2×81747450581² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81747450511) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6780251 + ... + 6792296.

It is an arithmetic number, because the mean of its divisors is an integer number (10790175660).

Almost surely, 2^81747450581 is an apocalyptic number.

It is an amenable number.

81747450581 is a deficient number, since it is larger than the sum of its proper divisors (4573954699).

81747450581 is a wasteful number, since it uses less digits than its factorization.

81747450581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13572883.

The product of its (nonzero) digits is 1254400, while the sum is 50.

The spelling of 81747450581 in words is "eighty-one billion, seven hundred forty-seven million, four hundred fifty thousand, five hundred eighty-one".