21662312321 has 16 divisors (see below), whose sum is σ = 23990773968. Its totient is φ = 19432243200.

The previous prime is 21662312293. The next prime is 21662312351. The reversal of 21662312321 is 12321326612.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 362369296 + 21299943025 = 19036^2 + 145945^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21662312321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21662312351) 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, 57911 + ... + 216051.

It is an arithmetic number, because the mean of its divisors is an integer number (1499423373).

Almost surely, 2^21662312321 is an apocalyptic number.

It is an amenable number.

21662312321 is a deficient number, since it is larger than the sum of its proper divisors (2328461647).

21662312321 is a wasteful number, since it uses less digits than its factorization.

21662312321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158452.

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

Adding to 21662312321 its reverse (12321326612), we get a palindrome (33983638933).

The spelling of 21662312321 in words is "twenty-one billion, six hundred sixty-two million, three hundred twelve thousand, three hundred twenty-one".