891131013221 has 2 divisors, whose sum is σ = 891131013222. Its totient is φ = 891131013220.

The previous prime is 891131013211. The next prime is 891131013229. The reversal of 891131013221 is 122310131198.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 587514585025 + 303616428196 = 766495^2 + 551014^2 .

It is a cyclic number.

It is not a de Polignac number, because 891131013221 - 2²² = 891126818917 is a prime.

It is a super-2 number, since 2×891131013221² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (891131013229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445565506610 + 445565506611.

It is an arithmetic number, because the mean of its divisors is an integer number (445565506611).

Almost surely, 2^891131013221 is an apocalyptic number.

It is an amenable number.

891131013221 is a deficient number, since it is larger than the sum of its proper divisors (1).

891131013221 is an equidigital number, since it uses as much as digits as its factorization.

891131013221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 32.

The spelling of 891131013221 in words is "eight hundred ninety-one billion, one hundred thirty-one million, thirteen thousand, two hundred twenty-one".