15855813 has 6 divisors (see below), whose sum is σ = 22902854. Its totient is φ = 10570536.

The previous prime is 15855811. The next prime is 15855839. The reversal of 15855813 is 31855851.

It can be written as a sum of positive squares in only one way, i.e., 15824484 + 31329 = 3978^2 + 177^2 .

It is not a de Polignac number, because 15855813 - 2¹ = 15855811 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15855811) 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, 880870 + ... + 880887.

Almost surely, 2^15855813 is an apocalyptic number.

It is an amenable number.

15855813 is a deficient number, since it is larger than the sum of its proper divisors (7047041).

15855813 is a wasteful number, since it uses less digits than its factorization.

15855813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1761763 (or 1761760 counting only the distinct ones).

The product of its digits is 24000, while the sum is 36.

The square root of 15855813 is about 3981.9358357462. The cubic root of 15855813 is about 251.2249904563.

The spelling of 15855813 in words is "fifteen million, eight hundred fifty-five thousand, eight hundred thirteen".