15661900505 has 8 divisors (see below), whose sum is σ = 19899826632. Its totient is φ = 11792489728.

The previous prime is 15661900453. The next prime is 15661900511. The reversal of 15661900505 is 50500916651.

It is a happy number.

15661900505 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 634082761 + 15027817744 = 25181^2 + 122588^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 15661900505 - 2¹⁸ = 15661638361 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 92128742 + ... + 92128911.

It is an arithmetic number, because the mean of its divisors is an integer number (2487478329).

Almost surely, 2^15661900505 is an apocalyptic number.

It is an amenable number.

15661900505 is a deficient number, since it is larger than the sum of its proper divisors (4237926127).

15661900505 is a wasteful number, since it uses less digits than its factorization.

15661900505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184257675.

The product of its (nonzero) digits is 40500, while the sum is 38.

The spelling of 15661900505 in words is "fifteen billion, six hundred sixty-one million, nine hundred thousand, five hundred five".