20988978797 has 2 divisors, whose sum is σ = 20988978798. Its totient is φ = 20988978796.

The previous prime is 20988978743. The next prime is 20988978811. The reversal of 20988978797 is 79787988902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13748500516 + 7240478281 = 117254^2 + 85091^2 .

It is a cyclic number.

It is not a de Polignac number, because 20988978797 - 2²⁶ = 20921869933 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20988978737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10494489398 + 10494489399.

It is an arithmetic number, because the mean of its divisors is an integer number (10494489399).

Almost surely, 2^20988978797 is an apocalyptic number.

It is an amenable number.

20988978797 is a deficient number, since it is larger than the sum of its proper divisors (1).

20988978797 is an equidigital number, since it uses as much as digits as its factorization.

20988978797 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 256048128, while the sum is 74.

The spelling of 20988978797 in words is "twenty billion, nine hundred eighty-eight million, nine hundred seventy-eight thousand, seven hundred ninety-seven".