21211220993 has 2 divisors, whose sum is σ = 21211220994. Its totient is φ = 21211220992.

The previous prime is 21211220981. The next prime is 21211221019. The reversal of 21211220993 is 39902211212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20583067024 + 628153969 = 143468^2 + 25063^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211220993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21211220963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605610496 + 10605610497.

It is an arithmetic number, because the mean of its divisors is an integer number (10605610497).

Almost surely, 2^21211220993 is an apocalyptic number.

It is an amenable number.

21211220993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211220993 is an equidigital number, since it uses as much as digits as its factorization.

21211220993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 32.

The spelling of 21211220993 in words is "twenty-one billion, two hundred eleven million, two hundred twenty thousand, nine hundred ninety-three".