21201011609 has 2 divisors, whose sum is σ = 21201011610. Its totient is φ = 21201011608.

The previous prime is 21201011597. The next prime is 21201011621. The reversal of 21201011609 is 90611010212.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (21201011597) and next prime (21201011621).

It can be written as a sum of positive squares in only one way, i.e., 18259576384 + 2941435225 = 135128^2 + 54235^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21201011609 is a prime.

It is not a weakly prime, because it can be changed into another prime (21201011639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600505804 + 10600505805.

It is an arithmetic number, because the mean of its divisors is an integer number (10600505805).

Almost surely, 2^21201011609 is an apocalyptic number.

It is an amenable number.

21201011609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201011609 is an equidigital number, since it uses as much as digits as its factorization.

21201011609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 23.

The spelling of 21201011609 in words is "twenty-one billion, two hundred one million, eleven thousand, six hundred nine".