21012121211 has 8 divisors (see below), whose sum is σ = 21097173504. Its totient is φ = 20927108520.

The previous prime is 21012121189. The next prime is 21012121213. The reversal of 21012121211 is 11212121012.

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 21012121211 - 2³⁴ = 3832252027 is a prime.

It is a super-2 number, since 2×21012121211² (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 (21012121213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1525646 + ... + 1539356.

It is an arithmetic number, because the mean of its divisors is an integer number (2637146688).

Almost surely, 2^21012121211 is an apocalyptic number.

21012121211 is a deficient number, since it is larger than the sum of its proper divisors (85052293).

21012121211 is a wasteful number, since it uses less digits than its factorization.

21012121211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19801.

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

Adding to 21012121211 its reverse (11212121012), we get a palindrome (32224242223).

The spelling of 21012121211 in words is "twenty-one billion, twelve million, one hundred twenty-one thousand, two hundred eleven".