21320226637 has 4 divisors (see below), whose sum is σ = 21322997116. Its totient is φ = 21317456160.

The previous prime is 21320226623. The next prime is 21320226659. The reversal of 21320226637 is 73662202312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15583527556 + 5736699081 = 124834^2 + 75741^2 .

It is a cyclic number.

It is not a de Polignac number, because 21320226637 - 2¹¹ = 21320224589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320223637) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1373664 + ... + 1389097.

It is an arithmetic number, because the mean of its divisors is an integer number (5330749279).

Almost surely, 2^21320226637 is an apocalyptic number.

It is an amenable number.

21320226637 is a deficient number, since it is larger than the sum of its proper divisors (2770479).

21320226637 is an equidigital number, since it uses as much as digits as its factorization.

21320226637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2770478.

The product of its (nonzero) digits is 36288, while the sum is 34.

Adding to 21320226637 its reverse (73662202312), we get a palindrome (94982428949).

The spelling of 21320226637 in words is "twenty-one billion, three hundred twenty million, two hundred twenty-six thousand, six hundred thirty-seven".