21516783733 has 2 divisors, whose sum is σ = 21516783734. Its totient is φ = 21516783732.

The previous prime is 21516783727. The next prime is 21516783787. The reversal of 21516783733 is 33738761512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17847089649 + 3669694084 = 133593^2 + 60578^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21516783733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21516783793) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10758391866 + 10758391867.

It is an arithmetic number, because the mean of its divisors is an integer number (10758391867).

Almost surely, 2^21516783733 is an apocalyptic number.

It is an amenable number.

21516783733 is a deficient number, since it is larger than the sum of its proper divisors (1).

21516783733 is an equidigital number, since it uses as much as digits as its factorization.

21516783733 is an evil number, because the sum of its binary digits is even.

The product of its digits is 635040, while the sum is 46.

The spelling of 21516783733 in words is "twenty-one billion, five hundred sixteen million, seven hundred eighty-three thousand, seven hundred thirty-three".