15801561 has 12 divisors (see below), whose sum is σ = 23670192. Its totient is φ = 10534212.

The previous prime is 15801509. The next prime is 15801563. The reversal of 15801561 is 16510851.

It is not a de Polignac number, because 15801561 - 2⁶ = 15801497 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (15801563) 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 11 ways as a sum of consecutive naturals, for example, 32271 + ... + 32756.

It is an arithmetic number, because the mean of its divisors is an integer number (1972516).

Almost surely, 2^15801561 is an apocalyptic number.

It is an amenable number.

15801561 is a deficient number, since it is larger than the sum of its proper divisors (7868631).

15801561 is an frugal number, since it uses more digits than its factorization.

15801561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65042 (or 65030 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 27.

The square root of 15801561 is about 3975.1177341055. The cubic root of 15801561 is about 250.9381338825.

The spelling of 15801561 in words is "fifteen million, eight hundred one thousand, five hundred sixty-one".