20409903989 has 2 divisors, whose sum is σ = 20409903990. Its totient is φ = 20409903988.

The previous prime is 20409903973. The next prime is 20409903991. The reversal of 20409903989 is 98930990402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20351304964 + 58599025 = 142658^2 + 7655^2 .

It is a cyclic number.

It is not a de Polignac number, because 20409903989 - 2⁴ = 20409903973 is a prime.

It is a super-2 number, since 2×20409903989² (a number of 21 digits) contains 22 as substring.

Together with 20409903991, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20409903989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20409903919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10204951994 + 10204951995.

It is an arithmetic number, because the mean of its divisors is an integer number (10204951995).

Almost surely, 2^20409903989 is an apocalyptic number.

It is an amenable number.

20409903989 is a deficient number, since it is larger than the sum of its proper divisors (1).

20409903989 is an equidigital number, since it uses as much as digits as its factorization.

20409903989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1259712, while the sum is 53.

The spelling of 20409903989 in words is "twenty billion, four hundred nine million, nine hundred three thousand, nine hundred eighty-nine".