21220211993 has 2 divisors, whose sum is σ = 21220211994. Its totient is φ = 21220211992.

The previous prime is 21220211989. The next prime is 21220212011. The reversal of 21220211993 is 39911202212.

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., 17639027344 + 3581184649 = 132812^2 + 59843^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220211993 - 2² = 21220211989 is a prime.

It is a super-2 number, since 2×21220211993² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21220214993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610105996 + 10610105997.

It is an arithmetic number, because the mean of its divisors is an integer number (10610105997).

Almost surely, 2^21220211993 is an apocalyptic number.

It is an amenable number.

21220211993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220211993 is an equidigital number, since it uses as much as digits as its factorization.

21220211993 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.

It can be divided in two parts, 212202119 and 93, that added together give a palindrome (212202212).

The spelling of 21220211993 in words is "twenty-one billion, two hundred twenty million, two hundred eleven thousand, nine hundred ninety-three".