21002001011 has 4 divisors (see below), whose sum is σ = 21049842000. Its totient is φ = 20954160024.

The previous prime is 21002000989. The next prime is 21002001043. The reversal of 21002001011 is 11010020012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002001011 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 21002001011.

It is not an unprimeable number, because it can be changed into a prime (21002001091) 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, 23919836 + ... + 23920713.

It is an arithmetic number, because the mean of its divisors is an integer number (5262460500).

Almost surely, 2^21002001011 is an apocalyptic number.

21002001011 is a deficient number, since it is larger than the sum of its proper divisors (47840989).

21002001011 is an equidigital number, since it uses as much as digits as its factorization.

21002001011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47840988.

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21002001011 its reverse (11010020012), we get a palindrome (32012021023).

The spelling of 21002001011 in words is "twenty-one billion, two million, one thousand, eleven".