21211002121 has 8 divisors (see below), whose sum is σ = 21445291080. Its totient is φ = 20977865088.

The previous prime is 21211002103. The next prime is 21211002181. The reversal of 21211002121 is 12120011212.

It can be written as a sum of positive squares in 4 ways, for example, as 138415225 + 21072586896 = 11765^2 + 145164^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21211002121 - 2⁷ = 21211001993 is a prime.

It is a super-2 number, since 2×21211002121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21211002181) 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, 250926 + ... + 324631.

It is an arithmetic number, because the mean of its divisors is an integer number (2680661385).

Almost surely, 2^21211002121 is an apocalyptic number.

It is an amenable number.

21211002121 is a deficient number, since it is larger than the sum of its proper divisors (234288959).

21211002121 is a wasteful number, since it uses less digits than its factorization.

21211002121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 575963.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21211002121 its reverse (12120011212), we get a palindrome (33331013333).

Subtracting from 21211002121 its reverse (12120011212), we obtain a palindrome (9090990909).

The spelling of 21211002121 in words is "twenty-one billion, two hundred eleven million, two thousand, one hundred twenty-one".