15681601 has 4 divisors (see below), whose sum is σ = 16887892. Its totient is φ = 14475312.

The previous prime is 15681581. The next prime is 15681623. The reversal of 15681601 is 10618651.

It is a Cunningham number, because it is equal to 3960²+1.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2322576 + 13359025 = 1524^2 + 3655^2 .

It is a cyclic number.

It is not a de Polignac number, because 15681601 - 2⁵ = 15681569 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 15681601.

It is not an unprimeable number, because it can be changed into a prime (15681661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 603126 + ... + 603151.

It is an arithmetic number, because the mean of its divisors is an integer number (4221973).

Almost surely, 2^15681601 is an apocalyptic number.

It is an amenable number.

15681601 is a deficient number, since it is larger than the sum of its proper divisors (1206291).

15681601 is a wasteful number, since it uses less digits than its factorization.

15681601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1206290.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 15681601 is about 3960.0001262626. Note that the first 3 decimals coincide. The cubic root of 15681601 is about 250.3015082250.

The spelling of 15681601 in words is "fifteen million, six hundred eighty-one thousand, six hundred one".