1820621 has 4 divisors (see below), whose sum is σ = 1986144. Its totient is φ = 1655100.

The previous prime is 1820617. The next prime is 1820629. The reversal of 1820621 is 1260281.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1260281 = 11 ⋅114571.

It is a cyclic number.

It is not a de Polignac number, because 1820621 - 2² = 1820617 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1820593 and 1820602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1820629) 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, 82745 + ... + 82766.

It is an arithmetic number, because the mean of its divisors is an integer number (496536).

2^1820621 is an apocalyptic number.

1820621 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1820621 is a deficient number, since it is larger than the sum of its proper divisors (165523).

1820621 is a wasteful number, since it uses less digits than its factorization.

1820621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165522.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 1820621 is about 1349.3038946064. The cubic root of 1820621 is about 122.1067997876.

The spelling of 1820621 in words is "one million, eight hundred twenty thousand, six hundred twenty-one".