20988936989 has 2 divisors, whose sum is σ = 20988936990. Its totient is φ = 20988936988.

The previous prime is 20988936977. The next prime is 20988937009. The reversal of 20988936989 is 98963988902.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17600532889 + 3388404100 = 132667^2 + 58210^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20988936989 is a prime.

It is a super-2 number, since 2×20988936989² (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 (20988986989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10494468494 + 10494468495.

It is an arithmetic number, because the mean of its divisors is an integer number (10494468495).

Almost surely, 2^20988936989 is an apocalyptic number.

It is an amenable number.

20988936989 is a deficient number, since it is larger than the sum of its proper divisors (1).

20988936989 is an equidigital number, since it uses as much as digits as its factorization.

20988936989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120932352, while the sum is 71.

The spelling of 20988936989 in words is "twenty billion, nine hundred eighty-eight million, nine hundred thirty-six thousand, nine hundred eighty-nine".