1801621 has 4 divisors (see below), whose sum is σ = 1804972. Its totient is φ = 1798272.

The previous prime is 1801619. The next prime is 1801669. The reversal of 1801621 is 1261081.

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 239121 + 1562500 = 489^2 + 1250^2 .

It is a cyclic number.

It is not a de Polignac number, because 1801621 - 2¹ = 1801619 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1801601) 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, 666 + ... + 2011.

It is an arithmetic number, because the mean of its divisors is an integer number (451243).

2^1801621 is an apocalyptic number.

It is an amenable number.

1801621 is a deficient number, since it is larger than the sum of its proper divisors (3351).

1801621 is an equidigital number, since it uses as much as digits as its factorization.

1801621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3350.

The product of its (nonzero) digits is 96, while the sum is 19.

The square root of 1801621 is about 1342.2447615841. The cubic root of 1801621 is about 121.6805446941.

The spelling of 1801621 in words is "one million, eight hundred one thousand, six hundred twenty-one".