81021898911 has 64 divisors (see below), whose sum is σ = 120929402880. Its totient is φ = 48014778240.

The previous prime is 81021898897. The next prime is 81021898921. The reversal of 81021898911 is 11989812018.

It is a happy number.

It is not a de Polignac number, because 81021898911 - 2¹⁵ = 81021866143 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81021898921) 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 63 ways as a sum of consecutive naturals, for example, 35426010 + ... + 35428296.

It is an arithmetic number, because the mean of its divisors is an integer number (1889521920).

Almost surely, 2^81021898911 is an apocalyptic number.

81021898911 is a deficient number, since it is larger than the sum of its proper divisors (39907503969).

81021898911 is a wasteful number, since it uses less digits than its factorization.

81021898911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2836.

The product of its (nonzero) digits is 82944, while the sum is 48.

The spelling of 81021898911 in words is "eighty-one billion, twenty-one million, eight hundred ninety-eight thousand, nine hundred eleven".