21788357837 has 2 divisors, whose sum is σ = 21788357838. Its totient is φ = 21788357836.

The previous prime is 21788357831. The next prime is 21788357839. The reversal of 21788357837 is 73875388712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18399837316 + 3388520521 = 135646^2 + 58211^2 .

It is a cyclic number.

It is not a de Polignac number, because 21788357837 - 2²⁰ = 21787309261 is a prime.

Together with 21788357839, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21788357831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10894178918 + 10894178919.

It is an arithmetic number, because the mean of its divisors is an integer number (10894178919).

Almost surely, 2^21788357837 is an apocalyptic number.

It is an amenable number.

21788357837 is a deficient number, since it is larger than the sum of its proper divisors (1).

21788357837 is an equidigital number, since it uses as much as digits as its factorization.

21788357837 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15805440, while the sum is 59.

The spelling of 21788357837 in words is "twenty-one billion, seven hundred eighty-eight million, three hundred fifty-seven thousand, eight hundred thirty-seven".