21011121073 has 2 divisors, whose sum is σ = 21011121074. Its totient is φ = 21011121072.

The previous prime is 21011121059. The next prime is 21011121127. The reversal of 21011121073 is 37012111012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13788160929 + 7222960144 = 117423^2 + 84988^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011121073 - 2²¹ = 21009023921 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21011121073.

It is not a weakly prime, because it can be changed into another prime (21011121013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505560536 + 10505560537.

It is an arithmetic number, because the mean of its divisors is an integer number (10505560537).

Almost surely, 2^21011121073 is an apocalyptic number.

It is an amenable number.

21011121073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011121073 is an equidigital number, since it uses as much as digits as its factorization.

21011121073 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84, while the sum is 19.

Adding to 21011121073 its reverse (37012111012), we get a palindrome (58023232085).

The spelling of 21011121073 in words is "twenty-one billion, eleven million, one hundred twenty-one thousand, seventy-three".