20021009509 has 2 divisors, whose sum is σ = 20021009510. Its totient is φ = 20021009508.

The previous prime is 20021009483. The next prime is 20021009537. The reversal of 20021009509 is 90590012002.

It is an a-pointer prime, because the next prime (20021009537) can be obtained adding 20021009509 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11505780225 + 8515229284 = 107265^2 + 92278^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021009509 - 2²¹ = 20018912357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20021009809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010504754 + 10010504755.

It is an arithmetic number, because the mean of its divisors is an integer number (10010504755).

Almost surely, 2^20021009509 is an apocalyptic number.

It is an amenable number.

20021009509 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021009509 is an equidigital number, since it uses as much as digits as its factorization.

20021009509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1620, while the sum is 28.

The spelling of 20021009509 in words is "twenty billion, twenty-one million, nine thousand, five hundred nine".