1428721 has 8 divisors (see below), whose sum is σ = 1664064. Its totient is φ = 1201200.

The previous prime is 1428709. The next prime is 1428751. The reversal of 1428721 is 1278241.

It is a happy number.

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

It is not a de Polignac number, because 1428721 - 2⁵ = 1428689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1428751) 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, 1555 + ... + 2296.

It is an arithmetic number, because the mean of its divisors is an integer number (208008).

2^1428721 is an apocalyptic number.

It is an amenable number.

1428721 is a deficient number, since it is larger than the sum of its proper divisors (235343).

1428721 is an equidigital number, since it uses as much as digits as its factorization.

1428721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3911.

The product of its digits is 896, while the sum is 25.

The square root of 1428721 is about 1195.2911779144. The cubic root of 1428721 is about 112.6287185123.

The spelling of 1428721 in words is "one million, four hundred twenty-eight thousand, seven hundred twenty-one".