21406213361 has 8 divisors (see below), whose sum is σ = 23098142760. Its totient is φ = 19720755072.

The previous prime is 21406213351. The next prime is 21406213369. The reversal of 21406213361 is 16331260412.

It can be written as a sum of positive squares in 4 ways, for example, as 1581573361 + 19824640000 = 39769^2 + 140800^2 .

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 21406213361 - 2²² = 21402019057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21406213369) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1610900 + ... + 1624133.

It is an arithmetic number, because the mean of its divisors is an integer number (2887267845).

Almost surely, 2^21406213361 is an apocalyptic number.

It is an amenable number.

21406213361 is a deficient number, since it is larger than the sum of its proper divisors (1691929399).

21406213361 is a wasteful number, since it uses less digits than its factorization.

21406213361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3235555.

The product of its (nonzero) digits is 5184, while the sum is 29.

Adding to 21406213361 its reverse (16331260412), we get a palindrome (37737473773).

The spelling of 21406213361 in words is "twenty-one billion, four hundred six million, two hundred thirteen thousand, three hundred sixty-one".