21211220389 has 4 divisors (see below), whose sum is σ = 21211651180. Its totient is φ = 21210789600.

The previous prime is 21211220377. The next prime is 21211220453. The reversal of 21211220389 is 98302211212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9595769764 + 11615450625 = 97958^2 + 107775^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211220389 - 2²³ = 21202831781 is a prime.

It is a super-2 number, since 2×21211220389² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21211220389.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211220309) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 130344 + ... + 243745.

It is an arithmetic number, because the mean of its divisors is an integer number (5302912795).

Almost surely, 2^21211220389 is an apocalyptic number.

It is an amenable number.

21211220389 is a deficient number, since it is larger than the sum of its proper divisors (430791).

21211220389 is an equidigital number, since it uses as much as digits as its factorization.

21211220389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 430790.

The product of its (nonzero) digits is 3456, while the sum is 31.

The spelling of 21211220389 in words is "twenty-one billion, two hundred eleven million, two hundred twenty thousand, three hundred eighty-nine".