21751038517 has 16 divisors (see below), whose sum is σ = 23726796912. Its totient is φ = 19819699200.

The previous prime is 21751038497. The next prime is 21751038539. The reversal of 21751038517 is 71583015712.

It can be written as a sum of positive squares in 8 ways, for example, as 20151121 + 21730887396 = 4489^2 + 147414^2 .

It is a cyclic number.

It is not a de Polignac number, because 21751038517 - 2³¹ = 19603554869 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21751038517.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21751033517) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 417903 + ... + 467059.

It is an arithmetic number, because the mean of its divisors is an integer number (1482924807).

Almost surely, 2^21751038517 is an apocalyptic number.

It is an amenable number.

21751038517 is a deficient number, since it is larger than the sum of its proper divisors (1975758395).

21751038517 is a wasteful number, since it uses less digits than its factorization.

21751038517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49608.

The product of its (nonzero) digits is 58800, while the sum is 40.

The spelling of 21751038517 in words is "twenty-one billion, seven hundred fifty-one million, thirty-eight thousand, five hundred seventeen".