81820166368 has 24 divisors (see below), whose sum is σ = 162893384640. Its totient is φ = 40450417920.

The previous prime is 81820166359. The next prime is 81820166369. The reversal of 81820166368 is 86366102818.

It is a super-2 number, since 2×81820166368² (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 (81820166369) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14361648 + ... + 14367343.

It is an arithmetic number, because the mean of its divisors is an integer number (6787224360).

Almost surely, 2^81820166368 is an apocalyptic number.

It is an amenable number.

81820166368 is a deficient number, since it is larger than the sum of its proper divisors (81073218272).

81820166368 is a wasteful number, since it uses less digits than its factorization.

81820166368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28729090 (or 28729082 counting only the distinct ones).

The product of its (nonzero) digits is 663552, while the sum is 49.

The spelling of 81820166368 in words is "eighty-one billion, eight hundred twenty million, one hundred sixty-six thousand, three hundred sixty-eight".