21011121001 has 8 divisors (see below), whose sum is σ = 22851395784. Its totient is φ = 19202851200.

The previous prime is 21011120993. The next prime is 21011121011. The reversal of 21011121001 is 10012111012.

It can be written as a sum of positive squares in 4 ways, for example, as 6199987600 + 14811133401 = 78740^2 + 121701^2 .

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

It is not a de Polignac number, because 21011121001 - 2³ = 21011120993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011121011) 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, 7999876 + ... + 8002501.

It is an arithmetic number, because the mean of its divisors is an integer number (2856424473).

Almost surely, 2^21011121001 is an apocalyptic number.

It is an amenable number.

21011121001 is a deficient number, since it is larger than the sum of its proper divisors (1840274783).

21011121001 is a wasteful number, since it uses less digits than its factorization.

21011121001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16002491.

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21011121001 its reverse (10012111012), we get a palindrome (31023232013).

The spelling of 21011121001 in words is "twenty-one billion, eleven million, one hundred twenty-one thousand, one".