81634529554 has 4 divisors (see below), whose sum is σ = 122451794334. Its totient is φ = 40817264776.

The previous prime is 81634529531. The next prime is 81634529563. The reversal of 81634529554 is 45592543618.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 45592543618 = 2 ⋅22796271809.

It can be written as a sum of positive squares in only one way, i.e., 76118051025 + 5516478529 = 275895^2 + 74273^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20408632387 + ... + 20408632390.

Almost surely, 2^81634529554 is an apocalyptic number.

81634529554 is a deficient number, since it is larger than the sum of its proper divisors (40817264780).

81634529554 is a wasteful number, since it uses less digits than its factorization.

81634529554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40817264779.

The product of its digits is 5184000, while the sum is 52.

The spelling of 81634529554 in words is "eighty-one billion, six hundred thirty-four million, five hundred twenty-nine thousand, five hundred fifty-four".