21122100021 has 16 divisors (see below), whose sum is σ = 30815889408. Its totient is φ = 12762591600.

The previous prime is 21122100019. The next prime is 21122100031. The reversal of 21122100021 is 12000122112.

It is not a de Polignac number, because 21122100021 - 2¹ = 21122100019 is a prime.

It is a super-2 number, since 2×21122100021² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122100031) 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, 955941 + ... + 977786.

It is an arithmetic number, because the mean of its divisors is an integer number (1925993088).

Almost surely, 2^21122100021 is an apocalyptic number.

It is an amenable number.

21122100021 is a deficient number, since it is larger than the sum of its proper divisors (9693789387).

21122100021 is a wasteful number, since it uses less digits than its factorization.

21122100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1934072.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21122100021 its reverse (12000122112), we get a palindrome (33122222133).

The spelling of 21122100021 in words is "twenty-one billion, one hundred twenty-two million, one hundred thousand, twenty-one".