81601547554 has 4 divisors (see below), whose sum is σ = 122402321334. Its totient is φ = 40800773776.

The previous prime is 81601547551. The next prime is 81601547591. The reversal of 81601547554 is 45574510618.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 58170204225 + 23431343329 = 241185^2 + 153073^2 .

It is not an unprimeable number, because it can be changed into a prime (81601547551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20400386887 + ... + 20400386890.

Almost surely, 2^81601547554 is an apocalyptic number.

81601547554 is a deficient number, since it is larger than the sum of its proper divisors (40800773780).

81601547554 is a wasteful number, since it uses less digits than its factorization.

81601547554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40800773779.

The product of its (nonzero) digits is 672000, while the sum is 46.

The spelling of 81601547554 in words is "eighty-one billion, six hundred one million, five hundred forty-seven thousand, five hundred fifty-four".