21011221097 has 2 divisors, whose sum is σ = 21011221098. Its totient is φ = 21011221096.

The previous prime is 21011221081. The next prime is 21011221129. The reversal of 21011221097 is 79012211012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20387270656 + 623950441 = 142784^2 + 24979^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011221097 - 2⁴ = 21011221081 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011221037) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505610548 + 10505610549.

It is an arithmetic number, because the mean of its divisors is an integer number (10505610549).

Almost surely, 2^21011221097 is an apocalyptic number.

It is an amenable number.

21011221097 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011221097 is an equidigital number, since it uses as much as digits as its factorization.

21011221097 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 26.

The spelling of 21011221097 in words is "twenty-one billion, eleven million, two hundred twenty-one thousand, ninety-seven".