21101212021 has 16 divisors (see below), whose sum is σ = 21627002880. Its totient is φ = 20582598960.

The previous prime is 21101211997. The next prime is 21101212031. The reversal of 21101212021 is 12021210112.

It is a cyclic number.

It is not a de Polignac number, because 21101212021 - 2¹¹ = 21101209973 is a prime.

It is a super-2 number, since 2×21101212021² (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 = 21101211992 and 21101212010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101212031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3028740 + ... + 3035698.

It is an arithmetic number, because the mean of its divisors is an integer number (1351687680).

Almost surely, 2^21101212021 is an apocalyptic number.

It is an amenable number.

21101212021 is a deficient number, since it is larger than the sum of its proper divisors (525790859).

21101212021 is a wasteful number, since it uses less digits than its factorization.

21101212021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7464.

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

Adding to 21101212021 its reverse (12021210112), we get a palindrome (33122422133).

The spelling of 21101212021 in words is "twenty-one billion, one hundred one million, two hundred twelve thousand, twenty-one".