21005004011 has 8 divisors (see below), whose sum is σ = 21542464944. Its totient is φ = 20468740480.

The previous prime is 21005003993. The next prime is 21005004019. The reversal of 21005004011 is 11040050012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21005004011 is a prime.

It is a super-3 number, since 3×21005004011³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21005004019) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 263765 + ... + 334038.

It is an arithmetic number, because the mean of its divisors is an integer number (2692808118).

Almost surely, 2^21005004011 is an apocalyptic number.

21005004011 is a deficient number, since it is larger than the sum of its proper divisors (537460933).

21005004011 is an equidigital number, since it uses as much as digits as its factorization.

21005004011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 598701.

The product of its (nonzero) digits is 40, while the sum is 14.

Adding to 21005004011 its reverse (11040050012), we get a palindrome (32045054023).

The spelling of 21005004011 in words is "twenty-one billion, five million, four thousand, eleven".