688798897921 has 2 divisors, whose sum is σ = 688798897922. Its totient is φ = 688798897920.

The previous prime is 688798897847. The next prime is 688798897937. The reversal of 688798897921 is 129798897886.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 624771680625 + 64027217296 = 790425^2 + 253036^2 .

It is a cyclic number.

It is not a de Polignac number, because 688798897921 - 2³⁵ = 654439159553 is a prime.

It is not a weakly prime, because it can be changed into another prime (688798817921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344399448960 + 344399448961.

It is an arithmetic number, because the mean of its divisors is an integer number (344399448961).

Almost surely, 2^688798897921 is an apocalyptic number.

It is an amenable number.

688798897921 is a deficient number, since it is larger than the sum of its proper divisors (1).

688798897921 is an equidigital number, since it uses as much as digits as its factorization.

688798897921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1755758592, while the sum is 82.

The spelling of 688798897921 in words is "six hundred eighty-eight billion, seven hundred ninety-eight million, eight hundred ninety-seven thousand, nine hundred twenty-one".