1921621 has 8 divisors (see below), whose sum is σ = 2109240. Its totient is φ = 1739712.

The previous prime is 1921573. The next prime is 1921631. The reversal of 1921621 is 1261291.

It can be written as a sum of positive squares in 4 ways, for example, as 260100 + 1661521 = 510^2 + 1289^2 .

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

It is a de Polignac number, because none of the positive numbers 2^k-1921621 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1921592 and 1921601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1921631) 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 7 ways as a sum of consecutive naturals, for example, 706 + ... + 2083.

It is an arithmetic number, because the mean of its divisors is an integer number (263655).

2^1921621 is an apocalyptic number.

It is an amenable number.

1921621 is a deficient number, since it is larger than the sum of its proper divisors (187619).

1921621 is a wasteful number, since it uses less digits than its factorization.

1921621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2855.

The product of its digits is 216, while the sum is 22.

The square root of 1921621 is about 1386.2254506393. The cubic root of 1921621 is about 124.3242683428.

The spelling of 1921621 in words is "one million, nine hundred twenty-one thousand, six hundred twenty-one".