91022021221 has 2 divisors, whose sum is σ = 91022021222. Its totient is φ = 91022021220.

The previous prime is 91022021183. The next prime is 91022021239. The reversal of 91022021221 is 12212022019.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72043928100 + 18978093121 = 268410^2 + 137761^2 .

It is a cyclic number.

It is not a de Polignac number, because 91022021221 - 2¹³ = 91022013029 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 91022021192 and 91022021201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91022021261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45511010610 + 45511010611.

It is an arithmetic number, because the mean of its divisors is an integer number (45511010611).

Almost surely, 2^91022021221 is an apocalyptic number.

It is an amenable number.

91022021221 is a deficient number, since it is larger than the sum of its proper divisors (1).

91022021221 is an equidigital number, since it uses as much as digits as its factorization.

91022021221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 22.

The spelling of 91022021221 in words is "ninety-one billion, twenty-two million, twenty-one thousand, two hundred twenty-one".