81542355840 has 192 divisors, whose sum is σ = 307173999600. Its totient is φ = 19767828480.

The previous prime is 81542355823. The next prime is 81542355859. The reversal of 81542355840 is 4855324518.

81542355840 is a `hidden beast` number, since 8 + 1 + 54 + 2 + 3 + 558 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (192).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 580125 + ... + 706844.

Almost surely, 2^81542355840 is an apocalyptic number.

81542355840 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81542355840 is an abundant number, since it is smaller than the sum of its proper divisors (225631643760).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81542355840 is a wasteful number, since it uses less digits than its factorization.

81542355840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1287005 (or 1286990 counting only the distinct ones).

The product of its (nonzero) digits is 768000, while the sum is 45.

The spelling of 81542355840 in words is "eighty-one billion, five hundred forty-two million, three hundred fifty-five thousand, eight hundred forty".