21500322197 has 2 divisors, whose sum is σ = 21500322198. Its totient is φ = 21500322196.

The previous prime is 21500322133. The next prime is 21500322253. The reversal of 21500322197 is 79122300512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14064536836 + 7435785361 = 118594^2 + 86231^2 .

It is a cyclic number.

It is not a de Polignac number, because 21500322197 - 2⁶ = 21500322133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21500222197) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750161098 + 10750161099.

It is an arithmetic number, because the mean of its divisors is an integer number (10750161099).

Almost surely, 2^21500322197 is an apocalyptic number.

It is an amenable number.

21500322197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21500322197 is an equidigital number, since it uses as much as digits as its factorization.

21500322197 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7560, while the sum is 32.

The spelling of 21500322197 in words is "twenty-one billion, five hundred million, three hundred twenty-two thousand, one hundred ninety-seven".