1287921 has 8 divisors (see below), whose sum is σ = 1723744. Its totient is φ = 855360.

The previous prime is 1287917. The next prime is 1287947. The reversal of 1287921 is 1297821.

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

It is not a de Polignac number, because 1287921 - 2² = 1287917 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1287961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 345 + ... + 1641.

It is an arithmetic number, because the mean of its divisors is an integer number (215468).

2^1287921 is an apocalyptic number.

It is an amenable number.

1287921 is a deficient number, since it is larger than the sum of its proper divisors (435823).

1287921 is a wasteful number, since it uses less digits than its factorization.

1287921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1631.

The product of its digits is 2016, while the sum is 30.

The square root of 1287921 is about 1134.8660713934. The cubic root of 1287921 is about 108.8002119824.

The spelling of 1287921 in words is "one million, two hundred eighty-seven thousand, nine hundred twenty-one".