21991220203 has 2 divisors, whose sum is σ = 21991220204. Its totient is φ = 21991220202.

The previous prime is 21991220197. The next prime is 21991220219. The reversal of 21991220203 is 30202219912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21991220203 - 2¹³ = 21991212011 is a prime.

It is a super-2 number, since 2×21991220203² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21991223203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10995610101 + 10995610102.

It is an arithmetic number, because the mean of its divisors is an integer number (10995610102).

Almost surely, 2^21991220203 is an apocalyptic number.

21991220203 is a deficient number, since it is larger than the sum of its proper divisors (1).

21991220203 is an equidigital number, since it uses as much as digits as its factorization.

21991220203 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 31.

The spelling of 21991220203 in words is "twenty-one billion, nine hundred ninety-one million, two hundred twenty thousand, two hundred three".