20401220309 has 2 divisors, whose sum is σ = 20401220310. Its totient is φ = 20401220308.

The previous prime is 20401220297. The next prime is 20401220327. The reversal of 20401220309 is 90302210402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20186158084 + 215062225 = 142078^2 + 14665^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20401220309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20401220009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10200610154 + 10200610155.

It is an arithmetic number, because the mean of its divisors is an integer number (10200610155).

Almost surely, 2^20401220309 is an apocalyptic number.

It is an amenable number.

20401220309 is a deficient number, since it is larger than the sum of its proper divisors (1).

20401220309 is an equidigital number, since it uses as much as digits as its factorization.

20401220309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 23.

The spelling of 20401220309 in words is "twenty billion, four hundred one million, two hundred twenty thousand, three hundred nine".