91004205521 has 2 divisors, whose sum is σ = 91004205522. Its totient is φ = 91004205520.

The previous prime is 91004205449. The next prime is 91004205577. The reversal of 91004205521 is 12550240019.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53807297296 + 37196908225 = 231964^2 + 192865^2 .

It is an emirp because it is prime and its reverse (12550240019) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91004205521 - 2²² = 91000011217 is a prime.

It is a super-3 number, since 3×91004205521³ (a number of 34 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (91004204521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45502102760 + 45502102761.

It is an arithmetic number, because the mean of its divisors is an integer number (45502102761).

Almost surely, 2^91004205521 is an apocalyptic number.

It is an amenable number.

91004205521 is a deficient number, since it is larger than the sum of its proper divisors (1).

91004205521 is an equidigital number, since it uses as much as digits as its factorization.

91004205521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3600, while the sum is 29.

The spelling of 91004205521 in words is "ninety-one billion, four million, two hundred five thousand, five hundred twenty-one".