81547801619 has 16 divisors (see below), whose sum is σ = 86706275040. Its totient is φ = 76430184960.

The previous prime is 81547801579. The next prime is 81547801637. The reversal of 81547801619 is 91610874518.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81547801619 - 2²⁴ = 81531024403 is a prime.

It is a super-2 number, since 2×81547801619² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81547801019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3978812 + ... + 3999254.

It is an arithmetic number, because the mean of its divisors is an integer number (5419142190).

Almost surely, 2^81547801619 is an apocalyptic number.

81547801619 is a deficient number, since it is larger than the sum of its proper divisors (5158473421).

81547801619 is a wasteful number, since it uses less digits than its factorization.

81547801619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21430.

The product of its (nonzero) digits is 483840, while the sum is 50.

The spelling of 81547801619 in words is "eighty-one billion, five hundred forty-seven million, eight hundred one thousand, six hundred nineteen".