15912121 has 3 divisors (see below), whose sum is σ = 15916111. Its totient is φ = 15908132.

The previous prime is 15912079. The next prime is 15912131. The reversal of 15912121 is 12121951.

The square root of 15912121 is 3989.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12121951 = 641 ⋅18911.

It can be written as a sum of positive squares in only one way, i.e., 7502121 + 8410000 = 2739^2 + 2900^2 .

It is not a de Polignac number, because 15912121 - 2⁷ = 15911993 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 15912092 and 15912101.

It is not an unprimeable number, because it can be changed into a prime (15912131) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1995 + ... + 5983.

Almost surely, 2^15912121 is an apocalyptic number.

15912121 is the 3989-th square number.

15912121 is the 1995-th centered octagonal number.

It is an amenable number.

15912121 is a deficient number, since it is larger than the sum of its proper divisors (3990).

15912121 is an frugal number, since it uses more digits than its factorization.

15912121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7978 (or 3989 counting only the distinct ones).

The product of its digits is 180, while the sum is 22.

The cubic root of 15912121 is about 251.5220269314.

The spelling of 15912121 in words is "fifteen million, nine hundred twelve thousand, one hundred twenty-one".