81796767840 has 120 divisors (see below), whose sum is σ = 288674472240. Its totient is φ = 21812467968.

The previous prime is 81796767821. The next prime is 81796767869. The reversal of 81796767840 is 4876769718.

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-2 number, since 2×81796767840² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3142780 + ... + 3168699.

It is an arithmetic number, because the mean of its divisors is an integer number (2405620602).

Almost surely, 2^81796767840 is an apocalyptic number.

81796767840 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81796767840 is an abundant number, since it is smaller than the sum of its proper divisors (206877704400).

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

81796767840 is a wasteful number, since it uses less digits than its factorization.

81796767840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6311506 (or 6311489 counting only the distinct ones).

The product of its (nonzero) digits is 28449792, while the sum is 63.

The spelling of 81796767840 in words is "eighty-one billion, seven hundred ninety-six million, seven hundred sixty-seven thousand, eight hundred forty".