21201420197 has 2 divisors, whose sum is σ = 21201420198. Its totient is φ = 21201420196.

The previous prime is 21201420181. The next prime is 21201420221. The reversal of 21201420197 is 79102410212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20680165636 + 521254561 = 143806^2 + 22831^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201420197 - 2⁴ = 21201420181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21201420127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600710098 + 10600710099.

It is an arithmetic number, because the mean of its divisors is an integer number (10600710099).

Almost surely, 2^21201420197 is an apocalyptic number.

It is an amenable number.

21201420197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201420197 is an equidigital number, since it uses as much as digits as its factorization.

21201420197 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 29.

The spelling of 21201420197 in words is "twenty-one billion, two hundred one million, four hundred twenty thousand, one hundred ninety-seven".