1421821 has 4 divisors (see below), whose sum is σ = 1441372. Its totient is φ = 1402272.

The previous prime is 1421813. The next prime is 1421857. The reversal of 1421821 is 1281241.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 912025 + 509796 = 955^2 + 714^2 .

It is a cyclic number.

It is not a de Polignac number, because 1421821 - 2³ = 1421813 is a prime.

It is a Duffinian number.

1421821 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1421801) 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, 9666 + ... + 9811.

It is an arithmetic number, because the mean of its divisors is an integer number (360343).

2^1421821 is an apocalyptic number.

It is an amenable number.

1421821 is a deficient number, since it is larger than the sum of its proper divisors (19551).

1421821 is an equidigital number, since it uses as much as digits as its factorization.

1421821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19550.

The product of its digits is 128, while the sum is 19.

The square root of 1421821 is about 1192.4013586037. The cubic root of 1421821 is about 112.4471125895.

The spelling of 1421821 in words is "one million, four hundred twenty-one thousand, eight hundred twenty-one".