81853782201 has 45 divisors (see below), whose sum is σ = 124090343509. Its totient is φ = 53770966344.

The previous prime is 81853782133. The next prime is 81853782203. The reversal of 81853782201 is 10228735818.

The square root of 81853782201 is 286101.

It is a perfect power (a square), and thus also a powerful number.

81853782201 is a `hidden beast` number, since 8 + 18 + 537 + 82 + 20 + 1 = 666.

It is not a de Polignac number, because 81853782201 - 2⁹ = 81853781689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81853782203) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 213717256 + ... + 213717638.

Almost surely, 2^81853782201 is an apocalyptic number.

81853782201 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

81853782201 is the 286101-st square number.

81853782201 is the 143051-st centered octagonal number.

It is an amenable number.

81853782201 is a deficient number, since it is larger than the sum of its proper divisors (42236561308).

81853782201 is an frugal number, since it uses more digits than its factorization.

81853782201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 944 (or 469 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The spelling of 81853782201 in words is "eighty-one billion, eight hundred fifty-three million, seven hundred eighty-two thousand, two hundred one".