21697053757 has 2 divisors, whose sum is σ = 21697053758. Its totient is φ = 21697053756.

The previous prime is 21697053737. The next prime is 21697053767. The reversal of 21697053757 is 75735079612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21646059876 + 50993881 = 147126^2 + 7141^2 .

It is a cyclic number.

It is not a de Polignac number, because 21697053757 - 2²³ = 21688665149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21697053737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10848526878 + 10848526879.

It is an arithmetic number, because the mean of its divisors is an integer number (10848526879).

Almost surely, 2^21697053757 is an apocalyptic number.

It is an amenable number.

21697053757 is a deficient number, since it is larger than the sum of its proper divisors (1).

21697053757 is an equidigital number, since it uses as much as digits as its factorization.

21697053757 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2778300, while the sum is 52.

The spelling of 21697053757 in words is "twenty-one billion, six hundred ninety-seven million, fifty-three thousand, seven hundred fifty-seven".