21003045643 has 4 divisors (see below), whose sum is σ = 21027497080. Its totient is φ = 20978594208.

The previous prime is 21003045619. The next prime is 21003045673. The reversal of 21003045643 is 34654030012.

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

It is not a de Polignac number, because 21003045643 - 2⁵ = 21003045611 is a prime.

It is a super-2 number, since 2×21003045643² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21003045673) 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, 12224430 + ... + 12226147.

It is an arithmetic number, because the mean of its divisors is an integer number (5256874270).

Almost surely, 2^21003045643 is an apocalyptic number.

21003045643 is a deficient number, since it is larger than the sum of its proper divisors (24451437).

21003045643 is an equidigital number, since it uses as much as digits as its factorization.

21003045643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24451436.

The product of its (nonzero) digits is 8640, while the sum is 28.

Adding to 21003045643 its reverse (34654030012), we get a palindrome (55657075655).

The spelling of 21003045643 in words is "twenty-one billion, three million, forty-five thousand, six hundred forty-three".