981191221 has 2 divisors, whose sum is σ = 981191222. Its totient is φ = 981191220.

The previous prime is 981191209. The next prime is 981191291. The reversal of 981191221 is 122191189.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 552908196 + 428283025 = 23514^2 + 20695^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-981191221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (981191291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 490595610 + 490595611.

It is an arithmetic number, because the mean of its divisors is an integer number (490595611).

Almost surely, 2^981191221 is an apocalyptic number.

It is an amenable number.

981191221 is a deficient number, since it is larger than the sum of its proper divisors (1).

981191221 is an equidigital number, since it uses as much as digits as its factorization.

981191221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 34.

The square root of 981191221 is about 31323.9719863238. The cubic root of 981191221 is about 993.6906832414.

The spelling of 981191221 in words is "nine hundred eighty-one million, one hundred ninety-one thousand, two hundred twenty-one".