21001002011 has 4 divisors (see below), whose sum is σ = 22910184024. Its totient is φ = 19091820000.

The previous prime is 21001001971. The next prime is 21001002019. The reversal of 21001002011 is 11020010012.

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

It is not a de Polignac number, because 21001002011 - 2⁶ = 21001001947 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 21001002011.

It is not an unprimeable number, because it can be changed into a prime (21001002019) 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, 954590990 + ... + 954591011.

It is an arithmetic number, because the mean of its divisors is an integer number (5727546006).

Almost surely, 2^21001002011 is an apocalyptic number.

21001002011 is a deficient number, since it is larger than the sum of its proper divisors (1909182013).

21001002011 is a wasteful number, since it uses less digits than its factorization.

21001002011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1909182012.

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

Adding to 21001002011 its reverse (11020010012), we get a palindrome (32021012023).

The spelling of 21001002011 in words is "twenty-one billion, one million, two thousand, eleven".