2015981 has 6 divisors (see below), whose sum is σ = 2216046. Its totient is φ = 1832600.

The previous prime is 2015977. The next prime is 2015999. The reversal of 2015981 is 1895102.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1713481 + 302500 = 1309^2 + 550^2 .

It is not a de Polignac number, because 2015981 - 2² = 2015977 is a prime.

It is a super-2 number, since 2×2015981² = 8128358784722, which contains 22 as substring.

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 2015981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2015921) 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 5 ways as a sum of consecutive naturals, for example, 8210 + ... + 8451.

It is an arithmetic number, because the mean of its divisors is an integer number (369341).

2^2015981 is an apocalyptic number.

It is an amenable number.

2015981 is a deficient number, since it is larger than the sum of its proper divisors (200065).

2015981 is a wasteful number, since it uses less digits than its factorization.

2015981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16683 (or 16672 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 2015981 is about 1419.8524571236. The cubic root of 2015981 is about 126.3267950907.

The spelling of 2015981 in words is "two million, fifteen thousand, nine hundred eighty-one".