20505561515 has 8 divisors (see below), whose sum is σ = 24663504768. Its totient is φ = 16366561920.

The previous prime is 20505561499. The next prime is 20505561553. The reversal of 20505561515 is 51516550502.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20505561515 - 2⁴ = 20505561499 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4733531 + ... + 4737860.

It is an arithmetic number, because the mean of its divisors is an integer number (3082938096).

Almost surely, 2^20505561515 is an apocalyptic number.

20505561515 is a deficient number, since it is larger than the sum of its proper divisors (4157943253).

20505561515 is an equidigital number, since it uses as much as digits as its factorization.

20505561515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9471829.

The product of its (nonzero) digits is 37500, while the sum is 35.

The spelling of 20505561515 in words is "twenty billion, five hundred five million, five hundred sixty-one thousand, five hundred fifteen".