81541778488 has 16 divisors (see below), whose sum is σ = 160937721000. Its totient is φ = 38625052896.

The previous prime is 81541778473. The next prime is 81541778489. The reversal of 81541778488 is 88487714518.

It is a super-2 number, since 2×81541778488² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81541778489) 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 3 ways as a sum of consecutive naturals, for example, 268229383 + ... + 268229686.

Almost surely, 2^81541778488 is an apocalyptic number.

It is an amenable number.

81541778488 is a deficient number, since it is larger than the sum of its proper divisors (79395942512).

81541778488 is a wasteful number, since it uses less digits than its factorization.

81541778488 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 536459094 (or 536459090 counting only the distinct ones).

The product of its digits is 16056320, while the sum is 61.

The spelling of 81541778488 in words is "eighty-one billion, five hundred forty-one million, seven hundred seventy-eight thousand, four hundred eighty-eight".