15685809049 has 3 divisors (see below), whose sum is σ = 15685934293. Its totient is φ = 15685683806.

The previous prime is 15685809023. The next prime is 15685809091. The reversal of 15685809049 is 94090858651.

The square root of 15685809049 is 125243.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 15685809049 - 2¹³ = 15685800857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15685809019) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 62622 + ... + 187864.

Almost surely, 2^15685809049 is an apocalyptic number.

15685809049 is the 125243-rd square number.

15685809049 is the 62622-nd centered octagonal number.

It is an amenable number.

15685809049 is a deficient number, since it is larger than the sum of its proper divisors (125244).

15685809049 is an frugal number, since it uses more digits than its factorization.

15685809049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 250486 (or 125243 counting only the distinct ones).

The product of its (nonzero) digits is 3110400, while the sum is 55.

The spelling of 15685809049 in words is "fifteen billion, six hundred eighty-five million, eight hundred nine thousand, forty-nine".