21001123121002 has 4 divisors (see below), whose sum is σ = 31501684681506. Its totient is φ = 10500561560500.

The previous prime is 21001123120933. The next prime is 21001123121009. The reversal of 21001123121002 is 20012132110012.

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

It can be written as a sum of positive squares in only one way, i.e., 20986926160201 + 14196960801 = 4581149^2 + 119151^2 .

It is not an unprimeable number, because it can be changed into a prime (21001123121009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5250280780249 + ... + 5250280780252.

Almost surely, 2^{21001123121002} is an apocalyptic number.

21001123121002 is a deficient number, since it is larger than the sum of its proper divisors (10500561560504).

21001123121002 is a wasteful number, since it uses less digits than its factorization.

21001123121002 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10500561560503.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21001123121002 its reverse (20012132110012), we get a palindrome (41013255231014).

The spelling of 21001123121002 in words is "twenty-one trillion, one billion, one hundred twenty-three million, one hundred twenty-one thousand, two".