15998405 has 8 divisors (see below), whose sum is σ = 19666584. Its totient is φ = 12486400.

The previous prime is 15998383. The next prime is 15998407. The reversal of 15998405 is 50489951.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 498436 + 15499969 = 706^2 + 3937^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 15998405 - 2⁶ = 15998341 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15998407) 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 7 ways as a sum of consecutive naturals, for example, 38816 + ... + 39225.

It is an arithmetic number, because the mean of its divisors is an integer number (2458323).

Almost surely, 2^15998405 is an apocalyptic number.

It is an amenable number.

15998405 is a deficient number, since it is larger than the sum of its proper divisors (3668179).

15998405 is an equidigital number, since it uses as much as digits as its factorization.

15998405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78087.

The product of its (nonzero) digits is 64800, while the sum is 41.

The square root of 15998405 is about 3999.8006200310. The cubic root of 15998405 is about 251.9758364754.

The spelling of 15998405 in words is "fifteen million, nine hundred ninety-eight thousand, four hundred five".