15871661 has 4 divisors (see below), whose sum is σ = 17092572. Its totient is φ = 14650752.

The previous prime is 15871627. The next prime is 15871673. The reversal of 15871661 is 16617851.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16617851 = 1181 ⋅14071.

It can be written as a sum of positive squares in 2 ways, for example, as 5593225 + 10278436 = 2365^2 + 3206^2 .

It is a cyclic number.

It is not a de Polignac number, because 15871661 - 2¹⁰ = 15870637 is a prime.

It is a super-3 number, since 3×15871661³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15871621) 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, 610436 + ... + 610461.

It is an arithmetic number, because the mean of its divisors is an integer number (4273143).

Almost surely, 2^15871661 is an apocalyptic number.

It is an amenable number.

15871661 is a deficient number, since it is larger than the sum of its proper divisors (1220911).

15871661 is a wasteful number, since it uses less digits than its factorization.

15871661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1220910.

The product of its digits is 10080, while the sum is 35.

The square root of 15871661 is about 3983.9253256054. The cubic root of 15871661 is about 251.3086629850.

The spelling of 15871661 in words is "fifteen million, eight hundred seventy-one thousand, six hundred sixty-one".