20958973657 has 2 divisors, whose sum is σ = 20958973658. Its totient is φ = 20958973656.

The previous prime is 20958973597. The next prime is 20958973687. The reversal of 20958973657 is 75637985902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20265230736 + 693742921 = 142356^2 + 26339^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20958973657 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20958973595 and 20958973604.

It is not a weakly prime, because it can be changed into another prime (20958973687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10479486828 + 10479486829.

It is an arithmetic number, because the mean of its divisors is an integer number (10479486829).

Almost surely, 2^20958973657 is an apocalyptic number.

It is an amenable number.

20958973657 is a deficient number, since it is larger than the sum of its proper divisors (1).

20958973657 is an equidigital number, since it uses as much as digits as its factorization.

20958973657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28576800, while the sum is 61.

The spelling of 20958973657 in words is "twenty billion, nine hundred fifty-eight million, nine hundred seventy-three thousand, six hundred fifty-seven".