21004140043 has 4 divisors (see below), whose sum is σ = 21008101680. Its totient is φ = 21000178408.

The previous prime is 21004140041. The next prime is 21004140077. The reversal of 21004140043 is 34004140012.

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 21004140043 - 2¹ = 21004140041 is a prime.

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 21004140043.

It is not an unprimeable number, because it can be changed into a prime (21004140041) 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, 1972855 + ... + 1983472.

It is an arithmetic number, because the mean of its divisors is an integer number (5252025420).

Almost surely, 2^21004140043 is an apocalyptic number.

21004140043 is a deficient number, since it is larger than the sum of its proper divisors (3961637).

21004140043 is an equidigital number, since it uses as much as digits as its factorization.

21004140043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3961636.

The product of its (nonzero) digits is 384, while the sum is 19.

Adding to 21004140043 its reverse (34004140012), we get a palindrome (55008280055).

The spelling of 21004140043 in words is "twenty-one billion, four million, one hundred forty thousand, forty-three".