21051110021 has 8 divisors (see below), whose sum is σ = 22168798080. Its totient is φ = 19934395488.

The previous prime is 21051109967. The next prime is 21051110023. The reversal of 21051110021 is 12001115012.

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 21051110021 - 2²² = 21046915717 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21051109978 and 21051110005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051110023) 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, 198776 + ... + 285681.

It is an arithmetic number, because the mean of its divisors is an integer number (2771099760).

Almost surely, 2^21051110021 is an apocalyptic number.

It is an amenable number.

21051110021 is a deficient number, since it is larger than the sum of its proper divisors (1117688059).

21051110021 is a wasteful number, since it uses less digits than its factorization.

21051110021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 486763.

The product of its (nonzero) digits is 20, while the sum is 14.

Adding to 21051110021 its reverse (12001115012), we get a palindrome (33052225033).

It can be divided in two parts, 21051 and 110021, that added together give a 17-th power (131072 = 2¹⁷).

The spelling of 21051110021 in words is "twenty-one billion, fifty-one million, one hundred ten thousand, twenty-one".