21711788557957 has 8 divisors (see below), whose sum is σ = 23610275634456. Its totient is φ = 19882337375232.

The previous prime is 21711788557939. The next prime is 21711788557961. The reversal of 21711788557957 is 75975588711712.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 15423575325796 + 6288213232161 = 3927286^2 + 2507631^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21711788557957 - 2¹¹ = 21711788555909 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21711788557957.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21711788554957) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17258972788 + ... + 17258974045.

It is an arithmetic number, because the mean of its divisors is an integer number (2951284454307).

Almost surely, 2^{21711788557957} is an apocalyptic number.

It is an amenable number.

21711788557957 is a deficient number, since it is larger than the sum of its proper divisors (1898487076499).

21711788557957 is a wasteful number, since it uses less digits than its factorization.

21711788557957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34517946887.

The product of its digits is 345744000, while the sum is 73.

The spelling of 21711788557957 in words is "twenty-one trillion, seven hundred eleven billion, seven hundred eighty-eight million, five hundred fifty-seven thousand, nine hundred fifty-seven".