1521665 has 8 divisors (see below), whose sum is σ = 1834368. Its totient is φ = 1211760.

The previous prime is 1521649. The next prime is 1521671. The reversal of 1521665 is 5661251.

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

It is not a de Polignac number, because 1521665 - 2⁴ = 1521649 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 794 + ... + 1916.

It is an arithmetic number, because the mean of its divisors is an integer number (229296).

It is a Proth number, since it is equal to 743 ⋅ 2¹¹ + 1 and 743 < 2¹¹.

2^1521665 is an apocalyptic number.

It is an amenable number.

1521665 is a deficient number, since it is larger than the sum of its proper divisors (312703).

1521665 is a wasteful number, since it uses less digits than its factorization.

1521665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1399.

The product of its digits is 1800, while the sum is 26.

The square root of 1521665 is about 1233.5578624450. The cubic root of 1521665 is about 115.0199083366.

The spelling of 1521665 in words is "one million, five hundred twenty-one thousand, six hundred sixty-five".