21771851013 has 18 divisors (see below), whose sum is σ = 34567063622. Its totient is φ = 13195060560.

The previous prime is 21771850987. The next prime is 21771851021. The reversal of 21771851013 is 31015817712.

It can be written as a sum of positive squares in only one way, i.e., 21555231489 + 216619524 = 146817^2 + 14718^2 .

It is not a de Polignac number, because 21771851013 - 2¹⁰ = 21771849989 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 (21771851063) 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 17 ways as a sum of consecutive naturals, for example, 9995170 + ... + 9997347.

Almost surely, 2^21771851013 is an apocalyptic number.

It is an amenable number.

21771851013 is a deficient number, since it is larger than the sum of its proper divisors (12795212609).

21771851013 is a wasteful number, since it uses less digits than its factorization.

21771851013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19992545 (or 19992531 counting only the distinct ones).

The product of its (nonzero) digits is 11760, while the sum is 36.

The spelling of 21771851013 in words is "twenty-one billion, seven hundred seventy-one million, eight hundred fifty-one thousand, thirteen".