20615506609 has 2 divisors, whose sum is σ = 20615506610. Its totient is φ = 20615506608.

The previous prime is 20615506607. The next prime is 20615506651. The reversal of 20615506609 is 90660551602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16699875984 + 3915630625 = 129228^2 + 62575^2 .

It is a cyclic number.

It is not a de Polignac number, because 20615506609 - 2¹ = 20615506607 is a prime.

It is a super-2 number, since 2×20615506609² (a number of 21 digits) contains 22 as substring.

Together with 20615506607, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20615506607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10307753304 + 10307753305.

It is an arithmetic number, because the mean of its divisors is an integer number (10307753305).

Almost surely, 2^20615506609 is an apocalyptic number.

It is an amenable number.

20615506609 is a deficient number, since it is larger than the sum of its proper divisors (1).

20615506609 is an equidigital number, since it uses as much as digits as its factorization.

20615506609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 97200, while the sum is 40.

The spelling of 20615506609 in words is "twenty billion, six hundred fifteen million, five hundred six thousand, six hundred nine".