891011011221 has 10 divisors (see below), whose sum is σ = 1331016448982. Its totient is φ = 594007340760.

The previous prime is 891011011217. The next prime is 891011011237. The reversal of 891011011221 is 122110110198.

891011011221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 887013610596 + 3997400625 = 941814^2 + 63225^2 .

It is not a de Polignac number, because 891011011221 - 2² = 891011011217 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (891011011621) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 5500067890 + ... + 5500068051.

Almost surely, 2^891011011221 is an apocalyptic number.

891011011221 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

891011011221 is a deficient number, since it is larger than the sum of its proper divisors (440005437761).

891011011221 is a wasteful number, since it uses less digits than its factorization.

891011011221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11000135953 (or 11000135944 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 27.

The spelling of 891011011221 in words is "eight hundred ninety-one billion, eleven million, eleven thousand, two hundred twenty-one".