20988986989 has 2 divisors, whose sum is σ = 20988986990. Its totient is φ = 20988986988.

The previous prime is 20988986971. The next prime is 20988987001. The reversal of 20988986989 is 98968988902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19670062500 + 1318924489 = 140250^2 + 36317^2 .

It is a cyclic number.

It is not a de Polignac number, because 20988986989 - 2¹³ = 20988978797 is a prime.

It is a super-2 number, since 2×20988986989² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20988936989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10494493494 + 10494493495.

It is an arithmetic number, because the mean of its divisors is an integer number (10494493495).

Almost surely, 2^20988986989 is an apocalyptic number.

It is an amenable number.

20988986989 is a deficient number, since it is larger than the sum of its proper divisors (1).

20988986989 is an equidigital number, since it uses as much as digits as its factorization.

20988986989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 322486272, while the sum is 76.

The spelling of 20988986989 in words is "twenty billion, nine hundred eighty-eight million, nine hundred eighty-six thousand, nine hundred eighty-nine".