2015561 has 6 divisors (see below), whose sum is σ = 2050650. Its totient is φ = 1981056.

The previous prime is 2015557. The next prime is 2015567. The reversal of 2015561 is 1655102.

It can be written as a sum of positive squares in only one way, i.e., 1795600 + 219961 = 1340^2 + 469^2 .

It is not a de Polignac number, because 2015561 - 2² = 2015557 is a prime.

It is a super-2 number, since 2×2015561² = 8124972289442, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a plaindrome in base 6.

It is not an unprimeable number, because it can be changed into a prime (2015567) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4265 + ... + 4713.

It is an arithmetic number, because the mean of its divisors is an integer number (341775).

2^2015561 is an apocalyptic number.

It is an amenable number.

2015561 is a deficient number, since it is larger than the sum of its proper divisors (35089).

2015561 is an frugal number, since it uses more digits than its factorization.

2015561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 583 (or 516 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 2015561 is about 1419.7045467279. The cubic root of 2015561 is about 126.3180217046.

The spelling of 2015561 in words is "two million, fifteen thousand, five hundred sixty-one".