21022001243 has 4 divisors (see below), whose sum is σ = 21105754488. Its totient is φ = 20938248000.

The previous prime is 21022001237. The next prime is 21022001257. The reversal of 21022001243 is 34210022012.

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

It is a cyclic number.

It is not a de Polignac number, because 21022001243 - 2⁴ = 21022001227 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21022007243) 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, 41876246 + ... + 41876747.

It is an arithmetic number, because the mean of its divisors is an integer number (5276438622).

Almost surely, 2^21022001243 is an apocalyptic number.

21022001243 is a deficient number, since it is larger than the sum of its proper divisors (83753245).

21022001243 is an equidigital number, since it uses as much as digits as its factorization.

21022001243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83753244.

The product of its (nonzero) digits is 192, while the sum is 17.

Adding to 21022001243 its reverse (34210022012), we get a palindrome (55232023255).

The spelling of 21022001243 in words is "twenty-one billion, twenty-two million, one thousand, two hundred forty-three".