21783437713 has 6 divisors (see below), whose sum is σ = 23140191926. Its totient is φ = 20502058752.

The previous prime is 21783437677. The next prime is 21783437743. The reversal of 21783437713 is 31773438712.

It can be written as a sum of positive squares in 3 ways, for example, as 16484762449 + 5298675264 = 128393^2 + 72792^2 .

It is not a de Polignac number, because 21783437713 - 2⁹ = 21783437201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21783437743) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 37687320 + ... + 37687897.

Almost surely, 2^21783437713 is an apocalyptic number.

It is an amenable number.

21783437713 is a deficient number, since it is larger than the sum of its proper divisors (1356754213).

21783437713 is an equidigital number, since it uses as much as digits as its factorization.

21783437713 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75375251 (or 75375234 counting only the distinct ones).

The product of its digits is 592704, while the sum is 46.

Subtracting 21783437713 from its reverse (31773438712), we obtain a palindrome (9990000999).

The spelling of 21783437713 in words is "twenty-one billion, seven hundred eighty-three million, four hundred thirty-seven thousand, seven hundred thirteen".