15900121 has 4 divisors (see below), whose sum is σ = 16329892. Its totient is φ = 15470352.

The previous prime is 15900119. The next prime is 15900133. The reversal of 15900121 is 12100951.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12100951 = 107 ⋅113093.

It can be written as a sum of positive squares in 2 ways, for example, as 12425625 + 3474496 = 3525^2 + 1864^2 .

It is a cyclic number.

It is not a de Polignac number, because 15900121 - 2¹ = 15900119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15900221) 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, 214830 + ... + 214903.

It is an arithmetic number, because the mean of its divisors is an integer number (4082473).

Almost surely, 2^15900121 is an apocalyptic number.

It is an amenable number.

15900121 is a deficient number, since it is larger than the sum of its proper divisors (429771).

15900121 is an equidigital number, since it uses as much as digits as its factorization.

15900121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 429770.

The product of its (nonzero) digits is 90, while the sum is 19.

The square root of 15900121 is about 3987.4955799349. The cubic root of 15900121 is about 251.4587832491.

The spelling of 15900121 in words is "fifteen million, nine hundred thousand, one hundred twenty-one".