20657987969 has 2 divisors, whose sum is σ = 20657987970. Its totient is φ = 20657987968.

The previous prime is 20657987873. The next prime is 20657988059. The reversal of 20657987969 is 96978975602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15079840000 + 5578147969 = 122800^2 + 74687^2 .

It is a cyclic number.

It is not a de Polignac number, because 20657987969 - 2²⁰ = 20656939393 is a prime.

It is a super-2 number, since 2×20657987969² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20657987899 and 20657987908.

It is not a weakly prime, because it can be changed into another prime (20657987069) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10328993984 + 10328993985.

It is an arithmetic number, because the mean of its divisors is an integer number (10328993985).

Almost surely, 2^20657987969 is an apocalyptic number.

It is an amenable number.

20657987969 is a deficient number, since it is larger than the sum of its proper divisors (1).

20657987969 is an equidigital number, since it uses as much as digits as its factorization.

20657987969 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 102876480, while the sum is 68.

The spelling of 20657987969 in words is "twenty billion, six hundred fifty-seven million, nine hundred eighty-seven thousand, nine hundred sixty-nine".