21054444121 has 16 divisors (see below), whose sum is σ = 22421298960. Its totient is φ = 19702159360.

The previous prime is 21054444113. The next prime is 21054444149. The reversal of 21054444121 is 12144445012.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 512388496 + 20542055625 = 22636^2 + 143325^2 .

It is a cyclic number.

It is not a de Polignac number, because 21054444121 - 2³ = 21054444113 is a prime.

It is a super-2 number, since 2×21054444121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21054444121.

It is not an unprimeable number, because it can be changed into a prime (21054444721) 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, 2378115 + ... + 2386951.

It is an arithmetic number, because the mean of its divisors is an integer number (1401331185).

Almost surely, 2^21054444121 is an apocalyptic number.

It is an amenable number.

21054444121 is a deficient number, since it is larger than the sum of its proper divisors (1366854839).

21054444121 is a wasteful number, since it uses less digits than its factorization.

21054444121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9644.

The product of its (nonzero) digits is 5120, while the sum is 28.

Adding to 21054444121 its reverse (12144445012), we get a palindrome (33198889133).

The spelling of 21054444121 in words is "twenty-one billion, fifty-four million, four hundred forty-four thousand, one hundred twenty-one".