15811138509 has 4 divisors (see below), whose sum is σ = 21081518016. Its totient is φ = 10540759004.

The previous prime is 15811138493. The next prime is 15811138513. The reversal of 15811138509 is 90583111851.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 15811138509 - 2⁴ = 15811138493 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15811138529) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2635189749 + ... + 2635189754.

It is an arithmetic number, because the mean of its divisors is an integer number (5270379504).

Almost surely, 2^15811138509 is an apocalyptic number.

It is an amenable number.

15811138509 is a deficient number, since it is larger than the sum of its proper divisors (5270379507).

15811138509 is an equidigital number, since it uses as much as digits as its factorization.

15811138509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5270379506.

The product of its (nonzero) digits is 43200, while the sum is 42.

The spelling of 15811138509 in words is "fifteen billion, eight hundred eleven million, one hundred thirty-eight thousand, five hundred nine".