21011001197 has 2 divisors, whose sum is σ = 21011001198. Its totient is φ = 21011001196.

The previous prime is 21011001127. The next prime is 21011001217. The reversal of 21011001197 is 79110011012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18134931556 + 2876069641 = 134666^2 + 53629^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011001197 - 2¹⁸ = 21010739053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21011001127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505500598 + 10505500599.

It is an arithmetic number, because the mean of its divisors is an integer number (10505500599).

Almost surely, 2^21011001197 is an apocalyptic number.

It is an amenable number.

21011001197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011001197 is an equidigital number, since it uses as much as digits as its factorization.

21011001197 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 126, while the sum is 23.

The spelling of 21011001197 in words is "twenty-one billion, eleven million, one thousand, one hundred ninety-seven".