21101212121 has 8 divisors (see below), whose sum is σ = 23100848544. Its totient is φ = 19115133120.

The previous prime is 21101212103. The next prime is 21101212123. The reversal of 21101212121 is 12121210112.

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

It is not a de Polignac number, because 21101212121 - 2⁶ = 21101212057 is a prime.

It is a super-2 number, since 2×21101212121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101212096 and 21101212105.

It is not an unprimeable number, because it can be changed into a prime (21101212123) 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, 3386096 + ... + 3392321.

It is an arithmetic number, because the mean of its divisors is an integer number (2887606068).

Almost surely, 2^21101212121 is an apocalyptic number.

It is an amenable number.

21101212121 is a deficient number, since it is larger than the sum of its proper divisors (1999636423).

21101212121 is a wasteful number, since it uses less digits than its factorization.

21101212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6778711.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21101212121 its reverse (12121210112), we get a palindrome (33222422233).

The spelling of 21101212121 in words is "twenty-one billion, one hundred one million, two hundred twelve thousand, one hundred twenty-one".