15505920785 has 4 divisors (see below), whose sum is σ = 18607104948. Its totient is φ = 12404736624.

The previous prime is 15505920761. The next prime is 15505920797. The reversal of 15505920785 is 58702950551.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3121792129 + 12384128656 = 55873^2 + 111284^2 .

It is a cyclic number.

It is not a de Polignac number, because 15505920785 - 2¹⁰ = 15505919761 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1550592074 + ... + 1550592083.

It is an arithmetic number, because the mean of its divisors is an integer number (4651776237).

Almost surely, 2^15505920785 is an apocalyptic number.

It is an amenable number.

15505920785 is a deficient number, since it is larger than the sum of its proper divisors (3101184163).

15505920785 is an equidigital number, since it uses as much as digits as its factorization.

15505920785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3101184162.

The product of its (nonzero) digits is 630000, while the sum is 47.

The spelling of 15505920785 in words is "fifteen billion, five hundred five million, nine hundred twenty thousand, seven hundred eighty-five".