21655340337 has 4 divisors (see below), whose sum is σ = 28873787120. Its totient is φ = 14436893556.

The previous prime is 21655340327. The next prime is 21655340339. The reversal of 21655340337 is 73304355612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21655340337 - 2⁸ = 21655340081 is a prime.

It is a super-2 number, since 2×21655340337² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21655340295 and 21655340304.

It is not an unprimeable number, because it can be changed into a prime (21655340339) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3609223387 + ... + 3609223392.

It is an arithmetic number, because the mean of its divisors is an integer number (7218446780).

Almost surely, 2^21655340337 is an apocalyptic number.

It is an amenable number.

21655340337 is a deficient number, since it is larger than the sum of its proper divisors (7218446783).

21655340337 is an equidigital number, since it uses as much as digits as its factorization.

21655340337 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7218446782.

The product of its (nonzero) digits is 226800, while the sum is 39.

Adding to 21655340337 its reverse (73304355612), we get a palindrome (94959695949).

The spelling of 21655340337 in words is "twenty-one billion, six hundred fifty-five million, three hundred forty thousand, three hundred thirty-seven".