15881561 has 4 divisors (see below), whose sum is σ = 16150800. Its totient is φ = 15612324.

The previous prime is 15881539. The next prime is 15881563. The reversal of 15881561 is 16518851.

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 15881561 - 2⁶ = 15881497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15881563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 134531 + ... + 134648.

It is an arithmetic number, because the mean of its divisors is an integer number (4037700).

Almost surely, 2^15881561 is an apocalyptic number.

It is an amenable number.

15881561 is a deficient number, since it is larger than the sum of its proper divisors (269239).

15881561 is an equidigital number, since it uses as much as digits as its factorization.

15881561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 269238.

The product of its digits is 9600, while the sum is 35.

The square root of 15881561 is about 3985.1676250818. The cubic root of 15881561 is about 251.3609036558.

The spelling of 15881561 in words is "fifteen million, eight hundred eighty-one thousand, five hundred sixty-one".