20191656997 has 2 divisors, whose sum is σ = 20191656998. Its totient is φ = 20191656996.

The previous prime is 20191656949. The next prime is 20191657019. The reversal of 20191656997 is 79965619102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16937981316 + 3253675681 = 130146^2 + 57041^2 .

It is a cyclic number.

It is not a de Polignac number, because 20191656997 - 2⁷ = 20191656869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20191656937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10095828498 + 10095828499.

It is an arithmetic number, because the mean of its divisors is an integer number (10095828499).

Almost surely, 2^20191656997 is an apocalyptic number.

It is an amenable number.

20191656997 is a deficient number, since it is larger than the sum of its proper divisors (1).

20191656997 is an equidigital number, since it uses as much as digits as its factorization.

20191656997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1837080, while the sum is 55.

The spelling of 20191656997 in words is "twenty billion, one hundred ninety-one million, six hundred fifty-six thousand, nine hundred ninety-seven".