1661421 has 8 divisors (see below), whose sum is σ = 2222080. Its totient is φ = 1104192.

The previous prime is 1661353. The next prime is 1661431. The reversal of 1661421 is 1241661.

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

It is not a de Polignac number, because 1661421 - 2⁷ = 1661293 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 660 + ... + 1938.

It is an arithmetic number, because the mean of its divisors is an integer number (277760).

2^1661421 is an apocalyptic number.

It is an amenable number.

1661421 is a deficient number, since it is larger than the sum of its proper divisors (560659).

1661421 is a wasteful number, since it uses less digits than its factorization.

1661421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1715.

The product of its digits is 288, while the sum is 21.

The square root of 1661421 is about 1288.9612096568. The cubic root of 1661421 is about 118.4385909099.

The spelling of 1661421 in words is "one million, six hundred sixty-one thousand, four hundred twenty-one".