21121002001 has 4 divisors (see below), whose sum is σ = 23041093104. Its totient is φ = 19200910900.

The previous prime is 21121001969. The next prime is 21121002029. The reversal of 21121002001 is 10020012112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21121002001 - 2⁵ = 21121001969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121006001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 960045535 + ... + 960045556.

It is an arithmetic number, because the mean of its divisors is an integer number (5760273276).

Almost surely, 2^21121002001 is an apocalyptic number.

It is an amenable number.

21121002001 is a deficient number, since it is larger than the sum of its proper divisors (1920091103).

21121002001 is a wasteful number, since it uses less digits than its factorization.

21121002001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1920091102.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21121002001 its reverse (10020012112), we get a palindrome (31141014113).

It can be divided in two parts, 2112 and 1002001, that multiplied together give a palindrome (2116226112).

The spelling of 21121002001 in words is "twenty-one billion, one hundred twenty-one million, two thousand, one".