1621091 has 4 divisors (see below), whose sum is σ = 1628400. Its totient is φ = 1613784.

The previous prime is 1621079. The next prime is 1621093. The reversal of 1621091 is 1901261.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1901261 = 31 ⋅61331.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1621091 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3311 + ... + 3768.

It is an arithmetic number, because the mean of its divisors is an integer number (407100).

2^1621091 is an apocalyptic number.

1621091 is a deficient number, since it is larger than the sum of its proper divisors (7309).

1621091 is an equidigital number, since it uses as much as digits as its factorization.

1621091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7308.

The product of its (nonzero) digits is 108, while the sum is 20.

The square root of 1621091 is about 1273.2207192785. The cubic root of 1621091 is about 117.4723882607.

The spelling of 1621091 in words is "one million, six hundred twenty-one thousand, ninety-one".