21211213993 has 2 divisors, whose sum is σ = 21211213994. Its totient is φ = 21211213992.

The previous prime is 21211213981. The next prime is 21211214027. The reversal of 21211213993 is 39931211212.

It is an a-pointer prime, because the next prime (21211214027) can be obtained adding 21211213993 to its sum of digits (34).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14521937049 + 6689276944 = 120507^2 + 81788^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211213993 - 2¹³ = 21211205801 is a prime.

It is not a weakly prime, because it can be changed into another prime (21211213943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605606996 + 10605606997.

It is an arithmetic number, because the mean of its divisors is an integer number (10605606997).

Almost surely, 2^21211213993 is an apocalyptic number.

It is an amenable number.

21211213993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211213993 is an equidigital number, since it uses as much as digits as its factorization.

21211213993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5832, while the sum is 34.

The spelling of 21211213993 in words is "twenty-one billion, two hundred eleven million, two hundred thirteen thousand, nine hundred ninety-three".